168:α-Granules are unique to platelets and are the most abundant of the platelet granules, numbering 50–80 per platelet 2. These granules measure 200–500 nm in diameter and account for about 10% of platelet volume. They contain mainly proteins, both membrane-associated receptors (for example, αIIbβ3 and P-selectin) and soluble cargo (for example, platelet factor 4 and fibrinogen). Proteomic studies have identified more than 300 soluble proteins that are involved in a wide variety of functions, including hemostasis (for example, von Willebrand factor and factor V), inflammation (for example, chemokines such as CXCL1 and interleukin-8), and wound healing (for example, vascular endothelial growth factor and fibroblast growth factor ) 3. The classic representation of α-granules as spherical organelles with a peripheral limiting membrane, a dense nucleoid, and progressively lucent peripheral zones on transmission electron microscopy is probably simplistic and may be in part a preparation artifact. Electron tomography with three-dimensional reconstruction of platelets is notable for a significant percentage of tubular α-granules that generally lack VWF 4. More recent work using transmission electron microscopy and freeze substitution dehydration of resting platelets shows that α-granules are ovoid with a generally homogeneous matrix and that tubes form from α-granules upon activation 5. Thus, whether or not there exists significant structural heterogeneity among α-granules remains to be completely resolved. α-Granule exocytosis is evaluated primarily by plasma membrane expression of P-selectin (CD62P) by flow cytometry or estimation of the release of PF4, VWF, or other granule cargos.
362:. Amylopectin forms the structure of the starch granule, with branching and non branching A-chains, B-chains, and C-chains. Amylose fills in the gaps of the amylopectin structure. Under a microscope, starch granules look like concentric layers, referred to as “growth rings”. Starch granules also contain granule-bound starch synthase and amylopectin synthesizing enzymes. Notably, starch granules vary in size and morphology across plant tissues and species.
347:
181:
electron-dense granule defined by the presence of Toll-like receptor 9 (TLR9) and protein disulfide isomerase (PDI), termed the T granule, has also been described, although its existence remains controversial. PDI and other platelet-borne thiol isomerases have been reported to be packaged within a non-granular compartment derived from the megakaryocyte endoplasmic reticulum (ER), which may be associated with the dense tubular system.
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190:
177:
their name from their electron-dense appearance on whole mount electron microscopy, which results from their high cation concentrations . Dense granule exocytosis is typically evaluated by ADP/ATP release by using luciferase-based luminescence techniques, release of preloaded serotonin, or membrane expression of lysosome-associated membrane protein 2 (LAMP2) or CD63 by flow cytometry.
590:
176:
of the type II alveolar cells, and lytic granules of cytotoxic T cells. Dense granules mainly contain bioactive amines (for example, serotonin and histamine), adenine nucleotides, polyphosphates, and pyrophosphates as well as high concentrations of cations, particularly calcium. These granules derive
342:
is an insoluble carbohydrate used for energy storage in plant cells. There are two forms of starch, transitionary starch and storage starch. Transitionary starch is synthesised via photosynthesis and found in photosythetic plant tissue cells, such as the leaves. Storage starch is reserved for longer
397:
Stress granule assembly is dependent upon the conditions of the cell. In yeast, stress granules form under conditions of high heat. Stress granules are of significance for their roles in mRNA localization, cell signaling pathways, and antiviral processes. Once disassembled, the RNA inside stress
180:
Other platelet granules have been described. Platelets contain about 1–3 lysosomes per platelet and peroxisomes, the platelet-specific function of which remains unclear. Lysosomal exocytosis is typically evaluated by estimation of released lysosomal enzymes such as beta hexosaminidase. An
398:
granules can go back to translation or be removed as cellular waste. Stress granules may provide protection for mRNA from interactions with the cytosol. Moreover, mutations that affect the formation or degradation of stress granules may contribute to neurodegenerative conditions such as
171:
Dense granules (also known as δ-granules) are the second most abundant platelet granules, with 3–8 per platelet. They measure about 150 nm in diameter 2. These granules, unique to the platelets, are a subtype of lysosome-related organelles (LROs), a group that also includes melanosomes,
208:, a hormone that regulates the concentration of glucose in the bloodstream to maintain homeostasis. The release of insulin by granules is signaled by plasma glucose concentrations and the resultant influx of calcium ions in pancreatic cells, which initiate granule
223:
transport. After budding, insulin secretory granules are acidified, activating endoproteases PC1/3 and PC2 to convert proinsulin into insulin. The clatherin coating is released and the insulin secretory granules are transported across the cell via
212:. Insulin release is biphastic, as insulin is first released in the primary phase by granules closest to the plasma membrane. In the secondary phase, insulin granules are recruited from reserves deeper in the beta cell for a slower release rate.
343:
periods of time and is found in non-photosynthetic tissue cells such as the roots or stem. Storage starch is utilized during germination or regrowth, or when energy demands exceed net energy production from photosynthesis.
690:
André J, Rouiller CH (1957) L'ultrastructure de la membrane nucléaire des ovocytes del l'araignée (Tegenaria domestica Clark). Proc
European Conf Electron Microscopy, Stockholm 1956. Academic Press, New York, pp 162
382:
or phosphorylation. They contain a “core” with high concentrations of proteins and mRNA and a less-concentrated outer region. Stress granules are dynamic in structure, and can dock and exchange with
378:(which account for 50% of the granule's components), and non-RNA binding proteins. They are formed via protein-protein interactions between mRNA binding proteins and are influenced by protein
56:
containing important components of cell phyisology. Examples of granules include granulocytes, platelet granules, insulin granules, germane granules, starch granules, and stress granules.
506:
Nordenfelt P, Winberg ME, Lönnbro P, Rasmusson B, Tapper H (December 2009). "Different requirements for early and late phases of azurophilic granule-phagosome fusion".
219:
molecules are synthesized in the endoplasmic reticulum and packaged in the golgi network. Insulin granules bud from the trans golgi network and are further sorted via
370:
Stress granules are composed of protein and RNA, and form from pools of mRNAs that have not started translation as a result of environmental conditions including
823:
1309:
145:. This tightly controlled process is initiated by immunological stimuli and results in the movement of granules to the cell membrane for fusion and release.
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91:
Neutrophils for example, contain primary granules, secondary granules, tertiary granules, and secretory vesicles. Primary vesicles, also known as
88:
which attack bacteria or parasites, and respond to allergens. Each type of granulocyte contains enzymes and chemicals tailored to its function.
248:
and fibrous structure occurred in drawings as early as in 1933 (Risley). Today, the nuage is accepted to represent a characteristic,
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that aid in pathogen distruction. Secondary granules, or specific granules, in neutrophils contain iron-binding protein
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31:
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374:, temperature, toxins, and osmotic pressure. Stress granules also contain translation initiation factors,
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204:. Insulin granules are secretory granules, which are responsible for the storage and secretion of
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with insulin granules, which are the dark black spots surrounded by a white area called a halo.
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Starch is stored in granule form. Starch granules are composed of a crystalline structure of
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72:, are white blood cells containing enzyme granules that play a significant role in the
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406:. However, the effects of stress granules on cell physiology are still under study.
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granules appear to be ancestral and universally conserved in the germlines of all
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or the cytoplasm. They can also perform fusion and fission in the cytoplasm.
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Insulin granules undergo a significant maturation process. First, precursor
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species for differential storage, asymmetric segregation (as needed for
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fate. The same granular material is also known under various synonyms:
205:
1024:
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317:
200:
Insulin granules are a specific type of granule found in pancreatic
388:
345:
188:
135:
302:
276:
clouds, yolk nuclei, Balbiani bodies, perinuclear P granules in
1234:
805:
141:
The process by which granule contents are released is known as
1154:
399:
593:
Text was copied from this source, which is available under a
297:
is a tightly interwoven network of differentially localized
309:), differential splicing and/or translational control. The
607:
Hutton JC (May 1989). "The insulin secretory granule".
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Creative
Commons Attribution 4.0 International License
1414:
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In 1957, André and
Rouiller first coined the term "
421:
419:
323:Many germline granule components are part of the
427:"Granulocytes: Definition, Types & Function"
758:"Principles and Properties of Stress Granules"
751:
749:
699:
697:
642:Omar-Hmeadi M, Idevall-Hagren O (March 2021).
1246:
817:
541:
539:
537:
393:Assembly and disassembly of stress granules.
8:
1310:Bactericidal permeability-increasing protein
546:Sharda A, Flaumenhaft R (28 February 2018).
457:"Mechanisms of degranulation in neutrophils"
49:. The term is most often used to describe a
644:"Insulin granule biogenesis and exocytosis"
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461:Allergy, Asthma, and Clinical Immunology
756:Protter DS, Parker R (September 2016).
415:
95:, secrete hydrolytic enzymes including
126:, contain granular enzymes, including
45:is a small particle barely visible by
548:"The life cycle of platelet granules"
7:
710:Cellular and Molecular Life Sciences
706:"Formation of starch in plant cells"
648:Cellular and Molecular Life Sciences
115:. Tertiary granules contain matrix
704:Pfister B, Zeeman SC (July 2016).
301:, which in turn localize specific
25:
350:Starch granules in potato cells.
588:
520:10.1111/j.1600-0854.2009.00986.x
288:in mice, and polar granules in
27:Small particle, often in plants
565:10.12688/f1000research.13283.1
1:
1406:Eosinophil-derived neurotoxin
988:Microtubule organizing center
266:of the cells destined to the
244:". (French for "cloud"). Its
138:of neighboring cells.
122:Other immune cells, such as
1396:Eosinophil cationic protein
1490:
660:10.1007/s00018-020-03688-4
29:
1441:
774:10.1016/j.tcb.2016.05.004
722:10.1007/s00018-016-2250-x
455:Lacy P (September 2006).
983:Prokaryotic cytoskeleton
474:10.1186/1710-1492-2-3-98
327:and function to repress
307:asymmetric cell division
32:Granule (disambiguation)
280:, germinal granules in
221:clathrin-coated vesicle
185:In beta cells (insulin)
76:. Granulocytes include
1448:platelet alpha-granule
762:Trends in Cell Biology
394:
351:
278:Caenorhabditis elegans
197:
134:which can lead to the
1401:Eosinophil peroxidase
973:Intermediate filament
866:Endoplasmic reticulum
392:
349:
329:transposable elements
192:
1343:Alkaline phosphatase
1275:Azurophilic granules
1220:Extracellular matrix
376:RNA binding proteins
299:RNA-binding proteins
124:natural killer cells
93:azurophilic granules
30:For other uses, see
1391:Major basic protein
923:Cytoplasmic granule
293:. Molecularly, the
18:Cytoplasmic granule
948:Weibel–Palade body
832:Structures of the
621:10.1007/BF00265542
395:
352:
335:In plants (starch)
258:encapsulating the
198:
157:are classified as
117:metalloproteinases
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1460:
1437:
1436:
1325:Specific granules
1228:
1227:
1008:Spindle pole body
716:(14): 2781–2807.
514:(12): 1881–1893.
286:chromatoid bodies
236:In germline cells
16:(Redirected from
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1331:
1295:serine proteases
1261:Contents of the
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654:(5): 1957–1970.
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431:Cleveland Clinic
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372:oxidative stress
264:nuclear envelope
153:The granules of
47:light microscopy
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1284:Myeloperoxidase
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1203:
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871:Golgi apparatus
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226:actin filaments
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174:lamellar bodies
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101:myeloperoxidase
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1143:Other internal
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768:(9): 668–679.
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615:(5): 271–281.
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282:Xenopus laevis
272:dense bodies,
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163:alpha granules
159:dense granules
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26:
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14:
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9:
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2:
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1358:NADPH oxidase
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1117:Proteinoplast
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1077:Mitochondrion
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1069:Endosymbionts
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1052:Lamellipodium
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968:Microfilament
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856:Cell membrane
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552:F1000Research
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467:(3): 98–108.
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143:degranulation
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74:immune system
71:
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60:In leukocytes
59:
57:
55:
52:
48:
44:
40:
33:
19:
1474:Cell anatomy
1445:
1368:Cathelicidin
1299:Proteinase 3
1267:granulocytes
1262:
1097:Gerontoplast
1047:Pseudopodium
1040:Radial spoke
1020:Undulipodium
960:Cytoskeleton
922:
876:Parenthesome
765:
761:
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612:
609:Diabetologia
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434:. Retrieved
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271:
262:face of the
239:
230:microtubules
214:
199:
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152:
149:In platelets
140:
121:
90:
70:granulocytes
63:
42:
39:cell biology
36:
1363:Collagenase
1348:Lactoferrin
1315:Collagenase
1199:Magnetosome
1165:Spliceosome
1092:Chromoplast
1087:Chloroplast
978:Microtubule
380:methylation
356:amylopectin
260:cytoplasmic
113:lactoferrin
82:eosinophils
78:neutrophils
64:A group of
1378:Eosinophil
1335:Neutrophil
1194:Proteasome
1187:Inclusions
1134:Nitroplast
1127:Apicoplast
1112:Elaioplast
1107:Amyloplast
1102:Leucoplast
1057:Filopodium
1003:Basal body
993:Centrosome
943:Peroxisome
938:Glyoxysome
928:Melanosome
838:organelles
436:2024-03-25
410:References
290:Drosophila
253:germ plasm
217:proinsulin
210:exocytosis
202:beta cells
105:cathepsins
66:leukocytes
1446:see also
1429:Histamine
1386:Cathepsin
1289:Defensins
1215:Cell wall
1177:Cytoplasm
1150:Nucleolus
1122:Tannosome
1030:Flagellum
1015:Myofibril
998:Centriole
933:Microbody
906:Phagosome
366:In stress
256:organelle
246:amorphous
194:Beta cell
155:platelets
132:proteases
109:defensins
86:basophils
68:, called
51:secretory
1468:Category
1416:Basophil
1353:Lysozyme
1305:Lysozyme
1293:neutral
1263:granules
1208:External
1160:Ribosome
916:Acrosome
901:Endosome
896:Lysosome
792:27289443
740:27166931
678:33146746
584:29560259
528:19804565
493:20525154
384:p-bodies
315:metazoan
311:germline
268:germline
128:perforin
97:elastase
1424:Heparin
1182:Cytosol
1082:Plastid
1035:Axoneme
911:Vacuole
891:Exosome
886:Vesicle
861:Nucleus
783:4993645
731:4919380
669:7966131
629:2526768
575:5832915
558:: 236.
508:Traffic
484:2876182
360:amylose
206:insulin
54:vesicle
43:granule
1025:Cilium
848:system
790:
780:
738:
728:
676:
666:
627:
582:
572:
526:
491:
481:
340:Starch
107:, and
84:, and
1170:Vault
318:phyla
295:nuage
242:nuage
136:lysis
1327:(2°)
1277:(1°)
834:cell
788:PMID
736:PMID
674:PMID
625:PMID
580:PMID
524:PMID
489:PMID
404:FTLD
402:and
358:and
303:mRNA
228:and
161:and
130:and
41:, a
1265:of
1155:RNA
778:PMC
770:doi
726:PMC
718:doi
691:164
664:PMC
656:doi
617:doi
570:PMC
560:doi
516:doi
479:PMC
469:doi
400:ALS
119:.
37:In
1470::
1450:,
836:/
786:.
776:.
766:26
764:.
760:.
748:^
734:.
724:.
714:73
712:.
708:.
696:^
672:.
662:.
652:78
650:.
646:.
623:.
613:32
611:.
578:.
568:.
554:.
550:.
536:^
522:.
512:10
510:.
487:.
477:.
463:.
459:.
445:^
429:.
418:^
331:.
320:.
284:,
232:.
165:.
103:,
99:,
80:,
1301:)
1297:(
1254:e
1247:t
1240:v
825:e
818:t
811:v
794:.
772::
742:.
720::
680:.
658::
631:.
619::
597:.
586:.
562::
556:7
530:.
518::
495:.
471::
465:2
439:.
34:.
20:)
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