The LRIG gene family has three vertebrate paralogs widely expressed in human and mouse tissues and a homolog in Ascidiacea.
Human LRIG1 (formerly LIG1), human LRIG2, and mouse Lrig1 (also known as Lig-1) encode integral membrane proteins. The human genes are located at chromosomes 3p14 and 1p13, which are regions frequently deleted in human cancers. We have searched for additional members of the LRIG family and by molecular cloning identified human LRIG3 and its mouse ortholog Lrig3. Human LRIG3 is located at chromosome 12q13. In silico analysis of public databases revealed a mouse Lrig2 mRNA, three LRIG homologs in the puffer fish Fugu rubripes, and one LRIG homolog in the ascidian tunicate Ciona intestinalis. The human and mouse LRIG polypeptides have the same predicted domain organization: a signal peptide, 15 tandem leucine-rich repeats with cysteine-rich N- and C-flanking domains, three immunoglobulin-like domains, a transmembrane domain, and a cytoplasmic tail. The extracellular part--especially the IgC2.2 domain, the transmembrane domain, and the membrane-proximal part of the cytoplasmic tail--are the most conserved regions. Northern blot analysis and real-time RT-PCR revealed that the three LRIG paralogs are widely expressed in human and mouse tissues. In conclusion, the LRIG gene family was found to have three widely expressed mammalian paralogs, corresponding orthologs in fish, and a homolog in Ascidiacea.
Guo
Dongsheng
D
Department of Radiation Sciences, Oncology, Umeå University, SE-90187 Umeå, Sweden.
Holmlund
Camilla
C
Henriksson
Roger
R
Hedman
Håkan
H
D000595:Amino Acid Sequence; D000818:Animals; D002878:Chromosomes, Human, Pair 1 / Q000235:genetics; D002893:Chromosomes, Human, Pair 3 / Q000235:genetics; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics*; D008565:Membrane Proteins / Q000235:genetics*; D051379:Mice; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009928:Organ Specificity / Q000235:genetics; D010802:Phylogeny; D017434:Protein Structure, Tertiary / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D023741:Takifugu / Q000235:genetics; D014561:Urochordata / Q000235:genetics*
C484445:LRIG1 protein, human; C488673:LRIG2 protein, human; C496406:LRIG3 protein, human; C101671:Lrig1 protein, mouse; C496407:Lrig3 protein, mouse; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins