Crystallin
In
Function
The main function of crystallins at least in the
Enzyme activity
Some crystallins are active
Classification
Crystallins from a vertebrate eye lens are classified into three main types: alpha, beta and gamma crystallins. These distinctions are based on the order in which they elute from a gel filtration chromatography column. These are also called ubiquitous crystallins. Beta- and gamma-crystallins (such as CRYGC) are similar in sequence, structure and domains topology, and thus have been grouped together as a protein superfamily called βγ-Crystallins. The α-crystallin family and βγ-crystallins compose the major family of proteins present in the crystalline lens. They occur in all vertebrate classes (though gamma-crystallins are low or absent in avian lenses); and delta-crystallin is found exclusively in reptiles and birds.[12][13]
In addition to these crystallins there are other taxon-specific crystallins which are only found in the lens of some organisms; these include delta, epsilon, tau, and iota-crystallins. For example, alpha, beta, and delta crystallins are found in avian and reptilian lenses, and the alpha, beta, and gamma families are found in the lenses of all other vertebrates.
Alpha-crystallin
Alpha crystallin A chain, N terminal | |||||||||
---|---|---|---|---|---|---|---|---|---|
Identifiers | |||||||||
Symbol | Crystallin | ||||||||
Pfam | PF00525 | ||||||||
InterPro | IPR003090 | ||||||||
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Alpha-crystallin occurs as large aggregates, comprising two types of related subunits (A and B) that are highly similar to the small (15-30kDa) heat shock proteins (
Alpha-crystallin has chaperone-like properties including the ability to prevent the precipitation of denatured proteins and to increase cellular tolerance to stress.[14] It has been suggested that these functions are important for the maintenance of lens transparency and the prevention of cataracts.[15] This is supported by the observation that alpha-crystallin mutations show an association with cataract formation.
The N-terminal domain of alpha-crystallin is not necessary for dimerisation or chaperone activity, but appears to be required for the formation of higher order aggregates.[16][17]
Beta and gamma crystallin
Beta/Gamma crystallin | |||||||||
---|---|---|---|---|---|---|---|---|---|
Identifiers | |||||||||
Symbol | Crystall | ||||||||
SCOP2 | 4gcr / SCOPe / SUPFAM | ||||||||
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Beta- and gamma- crystallin form a separate family.[18][19] Structurally, beta and gamma crystallins are composed of two similar domains which, in turn, are each composed of two similar motifs with the two domains connected by a short connecting peptide. Each motif, which is about forty amino acid residues long, is folded in a distinctive Greek key pattern. However, beta crystallin is an oligomer, composed of a complex group of molecules, whereas gamma crystallin is a simpler monomer.[20]
This section may require cleanup to meet Wikipedia's quality standards. The specific problem is: Lots of duplicate entries in the table. Please regenerate the table using only the "reviewed" entries. (March 2021) |
UniProt Entry name | Alternate Gene names | Length |
---|---|---|
AIM1L_HUMAN | AIM1L CRYBG2 | 616 |
AIM1_HUMAN | AIM1 CRYBG1 | 1723 |
ARLY_HUMAN | ASL | 464 |
CRBA1_HUMAN | CRYBA1 CRYB1 | 215 |
CRBA2_HUMAN | CRYBA2 | 197 |
CRBB1_HUMAN | CRYBB1 | 252 |
CRBA4_HUMAN | CRYBA4 | 196 |
CRBB2_HUMAN | CRYBB2 CRYB2 CRYB2A | 205 |
CRBB3_HUMAN | CRYBB3 CRYB3 | 211 |
CRBG3_HUMAN | CRYBG3 | 1022 |
CRBS_HUMAN | CRYGS CRYG8 | 178 |
CRGA_HUMAN | CRYGA CRYG1 | 174 |
CRGC_HUMAN | CRYGC CRYG3 | 174 |
CRGB_HUMAN | CRYGB CRYG2 | 175 |
CRGN_HUMAN | CRYGN | 182 |
CRGD_HUMAN | CRYGD CRYG4 | 174 |
CRYAA_HUMAN | CRYAA CRYA1 HSPB4 | 173 |
CRYAB_HUMAN | CRYAB CRYA2 | 175 |
CRYL1_HUMAN | CRYL1 CRY | 319 |
CRYM_HUMAN | CRYM THBP | 314 |
HSPB2_HUMAN | HSPB2 | 182 |
HSPB3_HUMAN | HSPB3 HSP27 HSPL27 | 150 |
HSPB8_HUMAN | HSPB8 CRYAC E2IG1 HSP22 PP1629 | 196 |
HSPB7_HUMAN | HSPB7 CVHSP | 170 |
HSPB9_HUMAN | HSPB9 | 159 |
HSPB1_HUMAN | HSPB1 HSP27 HSP28 | 205 |
HSPB6_HUMAN | HSPB6 | 160 |
IFT25_HUMAN | HSPB11 C1orf41 IFT25 HSPC034 | 144 |
MAF_HUMAN | MAF | 373 |
ODFP1_HUMAN | ODF1 ODFP | 250 |
QORL1_HUMAN | CRYZL1 4P11 | 349 |
QOR_HUMAN | CRYZ | 329 |
TITIN_HUMAN | TTN | 34350 |
ZEB1_HUMAN | ZEB1 AREB6 TCF8 | 1124 |
Q9UFA7_HUMAN | DKFZp434A0627 CRYGS hCG_16149 | 120 |
B4DU04_HUMAN | AIM1 hCG_33516 | 542 |
A8KAH6_HUMAN | HSPB2 hCG_39461 | 182 |
Q6ICS9_HUMAN | HSPB3 hCG_1736006 | 150 |
Q68DG0_HUMAN | DKFZp779D0968 HSPB7 | 174 |
Q8N241_HUMAN | HSPB7 hCG_23506 | 245 |
B4DLE8_HUMAN | CRYBG3 | 1365 |
C3VMY8_HUMAN | CRYAB | 175 |
R4UMM2_HUMAN | CRYBB2 | 205 |
B3KQL3_HUMAN | 119 | |
Q24JT5_HUMAN | CRYGA | 105 |
V9HWB6_HUMAN | HEL55 | 160 |
B4DNC2_HUMAN | 196 | |
V9HW27_HUMAN | HEL-S-101 | 175 |
H0YCW8_HUMAN | CRYAB | 106 |
E9PHE4_HUMAN | CRYAA | 136 |
E9PNH7_HUMAN | CRYAB | 106 |
E7EWH7_HUMAN | CRYAA | 153 |
B4DL87_HUMAN | 170 | |
V9HW43_HUMAN | HEL-S-102 | 205 |
E9PR44_HUMAN | CRYAB | 174 |
Q8IVN0_HUMAN | 86 | |
B7ZAH2_HUMAN | 542 | |
C9J5A3_HUMAN | HSPB7 | 124 |
E9PRS4_HUMAN | CRYAB | 69 |
K7EP04_HUMAN | HSPB6 | 137 |
I3L3Y1_HUMAN | CRYM | 97 |
H0YG30_HUMAN | HSPB8 | 152 |
H9KVC2_HUMAN | CRYM | 272 |
E9PS12_HUMAN | CRYAB | 77 |
E9PIR9_HUMAN | AIM1L | 787 |
B4DUL6_HUMAN | 80 | |
I3NI53_HUMAN | CRYM | 140 |
Q9NTH7_HUMAN | DKFZp434L1713 | 264 |
J3KQW1_HUMAN | AIM1L | 296 |
Q96QW7_HUMAN | AIM1 | 316 |
I3L2W5_HUMAN | CRYM | 165 |
B1AHR5_HUMAN | CRYBB3 | 113 |
B4DLI1_HUMAN | 403 | |
I3L325_HUMAN | CRYM | 241 |
Q7Z3C1_HUMAN | DKFZp686A14192 | 191 |
B4DWM9_HUMAN | 154 | |
Q71V83_HUMAN | CRYAA | 69 |
Q6P5P8_HUMAN | AIM1 | 326 |
C9JDH2_HUMAN | CRYBA2 | 129 |
B4DIA6_HUMAN | 155 | |
Q13684_HUMAN | 56 | |
F8WE04_HUMAN | HSPB1 | 186 |
J3QRT1_HUMAN | CRYBA1 | 75 |
E9PRA8_HUMAN | CRYAB | 155 |
E9PJL7_HUMAN | CRYAB | 130 |
C9J5N2_HUMAN | CRYBG3 | 229 |
I3L3J9_HUMAN | CRYM | 26 |
C9J659_HUMAN | CRYBG3 | 131 |
D3YTC6_HUMAN | HSPB7 | 165 |
References
- PMID 17997336.
- PMID 9396443.
- PMID 16395408.
- PMID 11053298.
- PMID 17264069.
- )
- ^ betagamma-crystallin AND calcium - PubMed result
- S2CID 562775.
- PMID 1370456.
- S2CID 45840536.
- S2CID 11128780.
- ^ PMID 2688200.
- S2CID 38532468.
- S2CID 72202184.
- PMID 21573059.
- PMID 9650080.
- PMID 11278766.
- S2CID 1411821.
- PMID 3064189.
- ISBN 9781857758849.
- ^ "Uniprot".
Further reading
- Graw J (1997). "The crystallins: Genes, proteins and diseases". Biological Chemistry. 378 (11): 1331–1348. PMID 9426193.
External links
- Crystallins at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
- alpha-Crystallins at the U.S. National Library of Medicine Medical Subject Headings (MeSH)
- Lens Crystallin Crystal Structures[permanent dead link] by Christine Slingsby, Birkbeck College
- Crystallins: Molecule of the Month Archived 2015-10-25 at the Wayback Machine, by David Goodsell, RCSB Protein Data Bank