Super-motifs and evolution of tandem leucine-rich repeats within the smallproteoglycans - Biglycan, decorin, lumican, fibromodulin, PRELP, keratocan, osteoadherin, epiphycan, and osteoglycin
N. Matsushima et al., Super-motifs and evolution of tandem leucine-rich repeats within the smallproteoglycans - Biglycan, decorin, lumican, fibromodulin, PRELP, keratocan, osteoadherin, epiphycan, and osteoglycin, PROTEINS, 38(2), 2000, pp. 210-225
Leucine-rich repeats (LRRs) with 20-30 amino acids in unit length are prese
nt in many proteins from prokaryotes to eukaryotes, The LRR-containing prot
eins include a family of nine small proteoglycans, forming three distinct s
ubfamilies: class I contains biglycan/PG-I and decorin/PG-II; class II: lum
ican, fibromodulin, PRELP, keratocan, and osteoadherin; and class III: epip
hycan/PG-Lb and osteoglycin or osteoinductive factor. Comparative sequence
analysis of the 34 available protein sequences reveals that these proteogly
cans have two types of LRRs, which we call S and T. The type S LRR is 21 re
sidues long and has the consensus sequence of xxaPzxLPxxLxLxxNxI. 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 ne; and I is ne or Leu. These type S and T LRRs are ordered in
to two super-motifs-STT with about 73 residues in classes I and II and ST w
ith 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 a
s (ST)T(ST)(2). Our analyses indicate that classes I/II and III evolved alo
ng 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 2000;38:210-225. (C) 2000 Wiley-Liss, Inc.