Institution: | 1. Sapporo Medical University Center for Medical Education, Sapporo, Hokkaido 060-8556, Japan;2. Sapporo Medical University School of Medicine, Sapporo, Hokkaido 060-8556, Japan;3. Sapporo City University School of Nursing, Sapporo, Hokkaido 060-0011, Japan;4. Hitotsubashi University Institute Economic Research, Kunitachi, Tokyo 186-8603, Japan |
Abstract: | BackgroundMany proteins have LRR (leucine-rich repeat) units interrupted by non-LRRs which we call IR (non-LRR island region).MethodsWe identified proteins containing LRR@IRs (LRRs having IR) by using a new method and then analyzed their natures and distributions.ResultsLRR@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.General significanceThis study suggests that various IRs and super motifs provide a great variety of structures and functions for LRRs. |