MOLECULAR RECOGNITION IN PROCOLLAGEN CHAIN ASSEMBLY

Recent advances in the understanding of the molecular recognition even ts occurring during the assembly of procollagen during biosynthesis ha ve come from the use of a semi-permeabilized cell-system that reconsti tutes the initial steps of chain assembly as they would occur in the e ndoplasmic reticulum of an intact cell. This has enabled a number of k ey questions concerning the molecular determinants of procollagen asse mbly to be addressed. In particular, the recognition events underlying the initial association of individual procollagen chains have been in vestigated, resulting in the identification of the key residues involv ed within the C-propeptide of fibrillar collagens. Similarly, the role of inter-chain disulfide bond formation in chain recognition and asse mbly has been investigated, along with the role of the C-propeptide, C -telopeptide and proline hydroxylation in helix nucleation, alignment and propagation. The results from these studies point to a two-stage r ecognition event, i.e., association of the chains driven by residues w ithin the C-propeptide followed by nucleation and alignment of the hel ix driven mainly by sequences present at the C-terminal end of the tri ple helical domain.