Role of the pro-alpha2(I) COOH-terminal region in assembly of type I collagen: disruption of two intramolecular disulfide bonds in pro-alpha2(I) blocks assembly of type I collagen

J Cell Biochem. 1998 Nov 1;71(2):233-42.


Collagen biosynthesis is a complex process that begins with the association of three procollagen chains. A series of conserved intra- and interchain disulfide bonds in the carboxyl-terminal region of the procollagen chains, or C-propeptide, has been hypothesized to play an important role in the nucleation and alignment of the chains. We tested this hypothesis by analyzing the ability of normal and cysteine-mutated pro-alpha2(I) chains to assemble into type I collagen heterotrimers when expressed in a cell line (D2) that produces only endogenous pro-alpha1(1). Pro-alpha2(I) chains containing single or double cysteine mutations that disrupted individual intra- or interchain disulfide bonds were able to form pepsin resistant type I collagen with pro-alpha1(I), indicating that individual disulfide bonds were not critical for assembly of the pro-alpha2(I) chain with pro-alpha1(I). Pro-alpha2(I) chains containing a triple cysteine mutation that disrupted both intrachain disulfide bonds were not able to form pepsin resistant type I collagen with pro-alpha1(I). Therefore, disruption of both pro-alpha2(I) intrachain disulfide bonds prevented the production and secretion of type I collagen heterotrimers. Although none of the individual disulfide bonds is essential for assembly of the procollagen chains, the presence of at least one intrachain disulfide bond may be necessary as a structural requirement for chain association or to stabilize the protein to prevent intracellular degradation.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alanine / genetics
  • Alanine / metabolism
  • Animals
  • Base Sequence
  • Cell Line
  • Cloning, Molecular
  • Collagen / chemistry
  • Collagen / genetics
  • Collagen / metabolism*
  • Cysteine / genetics
  • Cysteine / metabolism
  • DNA Primers
  • Dimerization
  • Disulfides / metabolism*
  • Mice
  • Mutagenesis, Site-Directed
  • Protein Precursors / chemistry
  • Protein Precursors / genetics
  • Protein Precursors / metabolism*
  • Protein Processing, Post-Translational


  • DNA Primers
  • Disulfides
  • Protein Precursors
  • Collagen
  • Cysteine
  • Alanine