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Components of the Collagen Prolyl 3-Hydroxylation Complex are Crucial for Normal Bone Development

Joan C. Marini, Wayne A. Cabral, Aileen M. Barnes and Weizhong Chang

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Prolyl 3-hydroxylase 1 (P3H1), cartilage-associated protein (CRTAP) and cyclophilin B (CyPB) form a complex in the endoplasmic reticulum which is responsible for 3-hydroxylation of a limited number of proline residues in types I, II and V collagens. In this complex, CRTAP serves the role of helper protein, while P3H1 provides the enzymatic activity for the modification. In type I collagen, the major protein of the extracellular matrix of bone, the complex 3-hydroxylates only the α1(I)Pro986 residue. P3H1 and CRTAP each also have independent roles as components of matrix. Furthermore, the two proteins have significant homology with each other. The critical importance of the components of the complex for normal bone development has been revealed by a Crtap knock-out mouse and by infants and children with null mutations of CRTAP and LEPRE1, the gene that encodes P3H1. On a clinical level, defects in the components of the prolyl 3-hydroxylation complex have been shown to be the long-sought cause of severe and lethal recessive osteogenesis imperfecta.

Authors

Joan C. Marini

National Institutes of Health; Bethesda, Maryland

Wayne A. Cabral

National Institutes of Health; Bethesda, Maryland

Aileen M. Barnes

National Institutes of Health; Bethesda, Maryland

Weizhong Chang

National Institutes of Health; Bethesda, Maryland

Purchase article for $19

Subscribe to this journal for $129/year