B. Font et al., CHARACTERIZATION OF THE INTERACTIONS OF TYPE-XII COLLAGEN WITH 2 SMALL PROTEOGLYCANS FROM FETAL BOVINE TENDON, DECORIN AND FIBROMODULIN, Matrix biology, 15(5), 1996, pp. 341-348
In addition to the major collagens, such as type I or type II, connect
ive tissues contain a number of less abundant collagens and proteoglyc
ans, whose association contributes to the different properties of the
tissues. Type XII and type XIV collagens have been described in soft c
onnective tissues, and type XIV collagen has been shown to interact sp
ecifically with decorin through its glycosaminoglycan chain (Font et a
l., J. Biol. Chem. 268, 25025-25018, 1993). Interactions between these
collagens and the small proteoglycans have been characterized further
by studying the binding of type XII: collagen to decorin by solid pha
se assays. Our results show a saturable binding of the proteoglycan th
rough its glycosaminoglycan chain to type XII collagen, which does not
seem to involve the large non-collagenous NC3 domain of the molecule.
This interaction is strongly inhibited by heparin. Furthermore, we re
port that another small proteoglycan, fibromodulin, isolated from tend
on under non-denaturing conditions, is able to bind to type XII collag
en. This interaction has been characterized and, unlike that observed
with decorin, type XII collagen-fibromodulin interaction seems to take
place with the core protein of the proteoglycan. In addition, we repo
rt that type XII-type I collagen interactions are not necessarily medi
ated by decorin as previously suggested.