Super-motifs and evolution of tandem leucine-rich repeats within the small proteoglycans—biglycan, decorin, lumican, fibromodulin, PRELP, keratocan, osteoadherin, epiphycan, and osteoglycin
✍ Scribed by Norio Matsushima; Toshio Ohyanagi; Takanori Tanaka; Robert H. Kretsinger
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 743 KB
- Volume
- 38
- Category
- Article
- ISSN
- 0887-3585
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✦ Synopsis
Leucine-rich repeats (LRRs) with 20 -30 amino acids in unit length are present in many proteins from prokaryotes to eukaryotes. The LRRcontaining proteins include a family of nine small proteoglycans, forming three distinct subfamilies: class I contains biglycan/PG-I and decorin/PG-II; class II: lumican, fibromodulin, PRELP, keratocan, and osteoadherin; and class III: epiphycan/PG-Lb and osteoglycin or osteoinductive factor. Comparative sequence analysis of the 34 available protein sequences reveals that these proteoglycans have two types of LRRs, which we call S and T. The type S LRR is 21 residues long and has the consensus sequence of xxaPzxLPxx-LxxLxLxxNxI. The type T LRR has 26 residues; its consensus sequence is zzxxaxxxxFxxaxxLxxLxLxxNxL. In both "x" indicates variable residue; "z" is frequently a gap; "a" is Val, Leu, or Ile; and I is Ile or Leu. These type S and T LRRs are ordered into two super-motifs-STT with about 73 residues in classes I and II and ST with about 47 residues in class III. The 12 LRRs in the small proteoglycans of I and II are best represented as (STT) 4 ; the seven LRRs of class III as (ST)T(ST) 2 . Our analyses indicate that classes I/II and III evolved along different paths after the establishment of the precursor ST, and classes I and II also diverged after the establishment of the precursor (STT) 4 . Proteins