title: Analyses of non-leucine-rich repeat (non-LRR) regions intervening between LRRs in proteins.
abstract: BACKGROUND
  Many proteins have LRR (leucine-rich repeat) units interrupted by non-LRRs which we call IR (non-LRR island region).
  
  
  METHODS
  We identified proteins containing LRR@IRs (LRRs having IR) by using a new method and then analyzed their natures and distributions.
  
  
  RESULTS
  LRR@IR proteins were found in over two hundred proteins from prokaryotes and from eukaryotes. These are divided into twenty-one different protein families. The IRs occur one to four times in LRR regions and range in length from 5 to 11,265 residues. The IR lengths in Fungi adenylate cyclases (acys) range from 5 to 116 residues; there are 22 LRR repeats. The IRs in Leishmania proteophosphoglycans (ppgs) vary from 105 to 11,265 residues. These results indicate that the IRs evolved rapidly. A group of LRR@IR proteins-LRRC17, chondroadherin-like protein, ppgs, and four Pseudomonas proteins-have a super motif consisting of an LRR block and its adjacent LRR@IR region. This indicates that the entire super motif experienced duplication. The sequence analysis of IRs offers functional similarity in some LRR@IR protein families.
  
  
  CONCLUSIONS
  This study suggests that various IRs and super motifs provide a great variety of structures and functions for LRRs.
authors: Sapporo Medical University Center for Medical Education, Sapporo, Hokkaido 060-8556, Japan. matusima@sapmed.ac.jp
authors: Norio
authors: N
authors: Matsushima
authors: Tomoko
authors: T
authors: Mikami
authors: Takanori
authors: T
authors: Tanaka
authors: Hiroki
authors: H
authors: Miyashita
authors: Keiko
authors: K
authors: Yamada
authors: Yoshio
authors: Y
authors: Kuroki
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D029681:Arabidopsis Proteins / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D029742:Caenorhabditis elegans Proteins / Q000235:genetics; D019295:Computational Biology / Q000379:methods*; D030562:Databases, Protein; D006801:Humans; D000090263:Leucine-Rich Repeat Proteins; D008565:Membrane Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D011506:Proteins / Q000145:classification / Q000235:genetics*; D011509:Proteoglycans / Q000235:genetics; D015800:Protozoan Proteins / Q000235:genetics; D020449:Repetitive Sequences, Amino Acid; D017386:Sequence Homology, Amino Acid
chemical_list: D029681:Arabidopsis Proteins; D001426:Bacterial Proteins; D029742:Caenorhabditis elegans Proteins; D000090263:Leucine-Rich Repeat Proteins; D008565:Membrane Proteins; C400527:Ppg1 protein, Leishmania; D011506:Proteins; D011509:Proteoglycans; D015800:Protozoan Proteins