A collagen-binding 59-kd protein (fibromodulin) is structurally related to the small interstitial proteoglycans PG-S1 and PG-S2 (decorin).

Abstract

We have determined the primary structure of a 59 kd collagen binding protein which is present in many types of connective tissues, e.g. cartilage, tendon, skin, sclera and cornea. The amino acid sequence, deducted from a 2662 bp cDNA clone, predicts a 42 kd protein with a high content of leucine residues. Most of the protein consists of homologous 23 amino acid residues repeats with predominantly leucine residues in conserved positions. Similar leucine rich repeats have been identified in a number of proteins including the small interstitial proteoglycans decorin and PG‐S1. The 59 kd protein and the two proteoglycans are homologous in their entire sequences suggesting that they have evolved from a common ancestral gene. The 59 kd protein and decorin are also functionally related in that both bind to collagen type I and II, and affect their fibrillogenesis. The substitution with glycosaminoglycan chains appears to be a feature shared by all three members of this family of leucine rich motif extracellular proteins, since the 59 kd protein isolated from cartilage is substituted with at least one keratan sulfate chain.

Thrombospondin‐4 is expressed by early osteogenic tissues in the chick embryo

“…The size of the avian TSP-4 transcript is in agreement with the sizes of amphibian (3.3 kb) and human (3.4 kb) TSP-4 mRNAs reported previously . It is similar in size to TSP-3 mRNA (3.5 kb in mouse, Vos et al, 1992; 3.4 kb in human, Lawler et al, 1993a), and is significantly larger than bovine COMP mRNA (2.5 kb, Oldberg et al, 1992). In addition, cTSP-4 hybridized to a 3.4 kb mRNA present in adult human heart and skeletal muscle (data not shown).…”

“…The other four family members have been designated thrombospondin-2 (TSP-2; Bornstein et al, 1991;LaBell et al, 1992), thrombospondin-3 (TSP-3; Vos et al, 1992), thrombospondin-4 (TSP-4; Lawler et al, 1993a), and cartilage oligomeric matrix protein (COMP; Oldberg et al, 1992: see reviews by Bornstein, 1992;Adams and Lawler, 1993a). On the basis of their primary structures, the thrombospondins can be divided into two subgroups (Lawler et al, 199313;Adams and Lawler, 1993a).…”

Age-related changes in the structure of the keratan sulphate chains attached to fibromodulin isolated from articular cartilage

“…Fibromodulin is exclusively glycosylated by short chains of keratan sulphate (KS) [13][14][15][16]. In addition, Plaas et al [17] have demonstrated that, in 3-month-old bovine articular cartilage, only four out of the five potential glycosylation sites were substituted by either KS or an N-linked oligosaccharide.…”

Chondroadherin Fragmentation Mediated by the Protease HTRA1 Distinguishes Human Intervertebral Disc Degeneration from Normal Aging

“…CHAD is also expressed in other tissues that experience load, such as bone and tendon, albeit in a lower abundance (9 -11). Thus, CHAD shows a very restricted distribution especially when compared with other leucine-rich repeat proteins (12)(13)(14).…”