title: Surface expression of Hsp70B' in response to proteasome inhibition in human colon cells.
abstract: Hsp70B' was expressed on the surface of HT-29 and CRL-1809 but not SW-480 human colon cell lines in response to proteasome inhibition as detected using flow cytometry. Surface expression was not detected under non-stress conditions nor was heat shock an inducer of surface expression in the three cell lines tested. Phylogenetic analysis indicated that the Hsp70B' protein sequence was most closely related to another major inducible human Hsp70, Hsp72. Hsp70B' appeared to be recently diverged, as homologs for Hsp70B' have not been found in rodents. Hsp72 and Hsp70B' shared 100% amino acid sequence identity in their predicted peptide-binding regions suggesting that they bind the same peptide substrates, perhaps in extracellular antigen presentation. Amino acid sequence differences were concentrated in the lid regions and the C-terminal domains raising the possibility that Hsp72 and Hsp70B' bind different co-chaperones or cell surface receptors.
authors.affiliation: Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269-3125, USA. emily.noonan@gmail.com
authors.forename: Emily J
authors.initials: EJ
authors.lastname: Noonan
authors.forename: Gregory
authors.initials: G
authors.lastname: Fournier
authors.forename: Lawrence E
authors.initials: LE
authors.lastname: Hightower
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology; D000595:Amino Acid Sequence; D001665:Binding Sites; D045744:Cell Line, Tumor / Q000378:metabolism; D002478:Cells, Cultured / Q000378:metabolism; D003106:Colon / Q000166:cytology / Q000378:metabolism*; D003110:Colonic Neoplasms / Q000473:pathology; D019143:Evolution, Molecular; D015870:Gene Expression; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D050884:HSP72 Heat-Shock Proteins / Q000737:chemistry; D006358:Hot Temperature; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D010802:Phylogeny; D061988:Proteasome Inhibitors; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D018840:HSP70 Heat-Shock Proteins; D050884:HSP72 Heat-Shock Proteins; C544598:HSPA6 protein, human; D008565:Membrane Proteins; D061988:Proteasome Inhibitors