title: Procollagen binds to both prolyl 4-hydroxylase/protein disulfide isomerase and HSP47 within the endoplasmic reticulum in the absence of ascorbate.
abstract: In cells, only properly folded procollagen trimers are secreted from the endoplasmic reticulum (ER), while improperly folded abnormal procollagens are retained within the ER. Ascorbic acid is a co-factor in procollagen hydroxylation, which in turn is required for trimer formation. We examined chaperone proteins which bound to procollagen in the absence of ascorbic acid, a model which mimics the human disease scurvy at the cellular level. We found that both prolyl 4-hydroxylase (P4-H)/protein disulfide isomerase (PDI) and HSP47 bound to procollagen in the absence of ascorbic acid. However, the binding of PDI to procollagen decreased when HSP47 was co-transfected, suggesting that HSP47 and PDI compete for binding to procollagen. These data indicate that P4-H/PDI and HSP47 have cooperative but distinct chaperone functions during procollagen biosynthesis.
authors.affiliation: Department of Molecular and Cellular Biology, Institute for Frontier Medical Sciences, Kyoto University, Sakyo-ku, Kyoto, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Hosokawa
authors.forename: K
authors.initials: K
authors.lastname: Nagata
mesh_terms: D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism; D002417:Cattle; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D050958:HSP47 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D018832:Molecular Chaperones / Q000378:metabolism; D011347:Procollagen / Q000235:genetics / Q000378:metabolism*; D011393:Procollagen-Proline Dioxygenase / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D014176:Protein Biosynthesis; D019704:Protein Disulfide-Isomerases / Q000737:chemistry / Q000378:metabolism*; D020836:Protein Structure, Quaternary; D011817:Rabbits; D014162:Transfection
chemical_list: D050958:HSP47 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D011347:Procollagen; C494660:SERPINH1 protein, human; D011393:Procollagen-Proline Dioxygenase; D019704:Protein Disulfide-Isomerases; D001205:Ascorbic Acid