Propeptide, role

Jager, S., Groll, M., Huber, R., Wolf, D. H., and Heinemeyer, W. Proteasome beta-type subunits unequal roles of propeptides in core particle maturation and a hierarchy of active site function./. Mol. Biol. 1999, 291, 997-1013. 

Figure 5.7. Diagram showing role of N- and C-propeptides in collagen self-assembly. The procollagen molecule is represented by a straight line with bent (N-propeptide) and circular (C-propeptide) regions. Initial linear and lateral aggregation is promoted by the presence of both the N- and C-propeptides. In the presence of both propeptides lateral assembly is limited and the fibrils are narrow. Removal of the N-propeptide results in lateral assembly of narrow fibrils removal of the C-propeptide results in additional lateral growth of fibrils. As indicated in the diagram, the presence of the N- and C-propeptides physically interferes with fibril formation.

However, it did not cross react with vWf with the use of antibodies specific for either species. With monoclonal antibodies and the N-terminal sequence of pre-vWf and of purified vWf antigen II it was established that the propeptide was identical to von Willebrand antigen II. An RGD sequence is also found in the propeptide. However, any role of the propeptide in hemostasis is uncertain (286). Another possible function for the propeptide is likely in the intracellular polymerization of the vWf subunits (see below). 

Collagen is synthesized in the cytoplasm of fibroblasts as larger precursor molecules (procollagen) where the triple helix is linked at the N-terminal part with peptides poor in glycine and hydroxyproline and at the C-terminal part with cystine-containing peptides (Fig. 1). The role of these propeptides is to prevent premature formation of collagen fibers in the fibroblasts. 

The Role of Propeptide Hormone Protein Conformation in Limited Endoproteolysis... 

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