A. Colombatti et al., SECRETION AND MATRIX ASSEMBLY OF RECOMBINANT TYPE-VI COLLAGEN, The Journal of biological chemistry, 270(22), 1995, pp. 13105-13111
A monomer of type VI collagen is composed of three different chains of
140 (alpha 1), 130 (alpha 2), and 250-350 kDa (alpha 3). Monomers ass
emble into dimers (6 chains) and tetramers (12 chains) that are stabil
ized by disulfide bonds and, once associated one to another, give rise
to a microfilamentous network in close apposition with cell surfaces
and banded collagen fibers. We have derived murine NIH/3T3 cell lines
that were transfected with the cDNAs for the three chains and that con
stitutively expressed chicken type VI collagen. Cotransfection was eff
icient because, in three out of six isolated cell lines, all chicken c
hains were expressed. Southern blotting demonstrated that several copi
es of each cDNA were integrated approximately in equal number. Express
ion of the three polypeptide chains was consistent with the levels of
the respective mRNAs. The three chicken chains assembled by disulfide
bonding to form correctly folded triple helical aggregated composites
with sizes corresponding to type VI collagen monomers, dimers, and tet
ramers. These functional recombinant assemblies were secreted and beca
me incorporated into the extracellular matrix, where they formed an ex
tensive fibrillar network.