Small heat shock protein IbpA, HSP20 family [Posttranslational modification, protein turnover, chaperones];

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|...
gi 148676852 119 GFEPDQVKVRVKDGKVCVSAERENRYDcLGSKKY-----SYMNICKEFSLPPCVDEKDVTYSY 176
Cdd:COG0071   19 GVDKEDIDVTVEGNVLTISGERKEEEE-EEGENYlrrerRYGSFERSFTLPDDVDVDKIEASY 80

Alpha-crystallin domain (ACD) of metazoan alpha-crystallin-type small(s) heat shock proteins (Hsps). sHsps are small stress induced proteins with monomeric masses between 12 -43 kDa, whose common feature is the Alpha-crystallin domain (ACD). sHsps are generally active as large oligomers consisting of multiple subunits, and are believed to be ATP-independent chaperones that prevent aggregation and are important in refolding in combination with other Hsps.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 148676852 114 SVNVCGFEPDQVKVRVKDGKVCVSAERENRYDclgSKKYSYMNICKEFSLPPCVDEKDVTYSYGLGSCVKIESPC 188
Cdd:cd06526   12 TLDVKGFKPEELKVKVSDNKLVVEGKHEERED---EHGYVSREFTRRYQLPEGVDPDSVTSSLSSDGVLTIEAPK 83

This domain family includes the alpha-crystallin domain (ACD) of alpha-crystallin-type small heat shock proteins (sHsps) and a similar domain found in p23-like proteins. sHsps are small stress induced proteins with monomeric masses between 12 -43 kDa, whose common feature is this ACD. sHsps are generally active as large oligomers consisting of multiple subunits, and are believed to be ATP-independent chaperones that prevent aggregation and are important in refolding in combination with other Hsps. p23 is a cochaperone of the Hsp90 chaperoning pathway. It binds Hsp90 and participates in the folding of a number of Hsp90 clients including the progesterone receptor. p23 also has a passive chaperoning activity. p23 in addition may act as the cytosolic prostaglandin E2 synthase. Included in this family is the p23-like C-terminal CHORD-SGT1 (CS) domain of suppressor of G2 allele of Skp1 (Sgt1) and the p23-like domains of human butyrate-induced transcript 1 (hB-ind1), NUD (nuclear distribution) C, Melusin, and NAD(P)H cytochrome b5 (NCB5) oxidoreductase (OR).

                         10        20        30        40        50        60
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 148676852 114 SVNVCGFEPDQVKVRVKDGKVCVSAERENRYDclgsKKYSYMNICKEFSLPPCVDEKDVTYSYGLG 179
Cdd:cd00298   11 TVDLPGVKKEDIKVEVEDNVLTISGKREEEEE----RERSYGEFERSFELPEDVDPEKSKASLENG 72

Alpha crystallin domain (ACD) found in mammalian small (s)heat shock protein (Hsp)-27 (also denoted HspB1 in human) and similar proteins. sHsps are molecular chaperones that suppress protein aggregation and protect against cell stress, and are generally active as large oligomers consisting of multiple subunits. Hsp27 shows enhanced synthesis in response to stress. It is a molecular chaperone which interacts with a large number of different proteins. It is found in many types of human cells including breast, uterus, cervix, platelets and cancer cells. Hsp27 has diverse cellular functions including, chaperoning, regulation of actin polymerization, keratinocyte differentiation, regulation of inflammatory pathways in keratinocytes, and protection from oxidative stress through modulating glutathione levels. It is also a subunit of AUF1-containing protein complexes. It has been linked to several transduction pathways regulating cellular functions including differentiation, cell growth, development, and apoptosis. Its activity can be regulated by phosphorylation. Its unphosphorylated state is a high molecular weight aggregated form (100-800kDa) composed of up to 24 subunits, which forms as a result of multiple interactions within the ACD, and is required for chaperone function and resistance to oxidative stress. Upon phosphorylation these large aggregates rapidly disassociate to smaller oligomers and chaperone activity is modified. High constitutive levels of Hsp27 have been detected in various cancer cells, in particular those of carcinoma origin. Over-expression of Hsp27 has a protective effect against various diseases-processes, including Huntington's disease. Mutations in Hsp27 have been associated with a form of distal hereditary motor neuropathy type II and Charcot-Marie-Tooth disease type 2.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*.
gi 148676852 114 SVNVCGFEPDQVKVRVKDGKVCVSAERENRYDclgskKYSYMNIC--KEFSLPPCVDEKDVTYSYGLGSCVKIESP 187
Cdd:cd06475   15 SLDVNHFAPEELVVKTKDGVVEITGKHEEKQD-----EHGFVSRCftRKYTLPPGVDPTAVTSSLSPDGILTVEAP 85

Alpha-crystallin domain (ACD) found in mammalian 21.6 KDa small heat shock protein (sHsp) HspB8, also denoted as Hsp22 in humans, and similar proteins. sHsps are molecular chaperones that suppress protein aggregation and protect against cell stress, and are generally active as large oligomers consisting of multiple subunits. A chaperone complex formed of HspB8 and Bag3 stimulates degradation of protein complexes by macroautophagy. HspB8 also forms complexes with Hsp27 (HspB1), MKBP (HspB2), HspB3, alphaB-crystallin (HspB5), Hsp20 (HspB6), and cvHsp (HspB7). These latter interactions may depend on phosphorylation of the respective partner sHsp. HspB8 may participate in the regulation of cell proliferation, cardiac hypertrophy, apoptosis, and carcinogenesis. Point mutations in HspB8 have been correlated with the development of several congenital neurological diseases, including Charcot Marie tooth disease and distal motor neuropathy type II.

                         10        20        30        40        50        60        70
                 ....*....|....*....|....*....|....*....|....*....|....*....|....*....|....*
gi 148676852 115 VNVCGFEPDQVKVRVKDGKVCVSAERENRYDCLG--SKkysymNICKEFSLPPCVDEKDVTYSYGLGSCVKIESP 187
Cdd:cd06480   21 VNVHSFKPEELTVKTKDGFVEVSGKHEEQQKEGGivSK-----NFTKKIQLPPEVDPVTVFASLSPEGLLIIEAP 90