Cartilage proteoglycan aggregates. The link protein and proteoglycan amino-terminal globular domains have similar structures.

P J Neame,J R Baker,J E Christner

doi:10.1016/s0021-9258(18)45445-2

Abstract

Cartilage proteoglycan aggregates contain two components (proteoglycan monomer and link protein) which interact with each other and with hyaluronic acid. Data from amino acid sequence analysis are presented that shows that a domain of the proteoglycan, the hyaluronic acid binding region, which interacts with link protein and hyaluronic acid is very similar to link protein in terms of its primary structure. However, the pattern of glycosylation in the hyaluronic acid binding region is different from that found in link protein. After removal of N-linked oligosaccharides, the tryptically prepared hyaluronic acid binding region from rat chondrosarcoma has a mass by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of 43 +/- 2 kDa. The COOH-terminal two-thirds of rat chondrosarcoma link protein, starting at residue 105, has 41.3% identity with a similar region in the hyaluronic acid binding region. We show that, in addition to the hyaluronic acid binding region, proteoglycan contains another region with similarity to the two repeating loop structures in the COOH-terminal two-thirds of link protein. This presumably corresponds to the second globular domain reported in rotary shadowing studies of cartilage proteoglycans. We have deduced the positions of all of the disulfide bonds in the hyaluronic acid binding region and find them to be in the same positions as would be expected from comparison of these sequences with link protein.

Highlights

From the Institute of Dental Research, Diabetes Research and Training Center, Atherosclerosis Research Unit, and Departments of
Data from amino acid sequence analysis arepresented that shows that a domain of the proteoglycan, the hyaluronic acid binding region, which interacts with link protein and hyaluronic acid is very similar to link protein in terms of its primary structure
As rat chondrosarcoma contains only one major aggregating chondroitin sulfate PG(11,12), we have utilized it asa source for HABR

Summary

Introduction

This is in good agreement with the Evidence is presented for a further region of PG which is value of 43 f 2 kDa found by SDS-PAGE of the deglycosylated similar to the COOH-terminal loops in LP but which is not HABR (Fig. Ml). The results correlate well with rotary shadow- NHZ-terminal sequence, its degree of glycosylation (considing studies which have shown two globular domains in PG at erably higher than LPfrom RC-PG aggregates),its molecular the end of the molecule which contains the HABR (22).

Results

Conclusion