Genomic structure and alternative splicing of the insulin receptor tyrosine kinase substrate of 53-kDa protein

Abstract

Insulin receptor tyrosine kinase substrate of 53-kDa protein (IRSp53) is now known to be a key factor in cytoskeleton reorganization. The human IRSp53 was identified as a binding partner with DRPLA protein, a product of the gene responsible for a neurodegenerative disorder, dentatorubral pallidoluysian atrophy, as well as a binding partner with brain-specific angiogenesis inhibitor 1. Previous studies identified at least four isoforms (L-, M-, S-and T-forms) in human, where 511 amino acid residues from the N-terminus were identical, followed by unique sequences of 9-41 amino acid residues. As each isoform had a distinct function, the unique sequences at the C-terminus had a vital role in its function. Here we report that these isoforms were indeed generated by alternative splicing, which was established by experimental and computational studies on human and rodent genomes. Previous biochemical reports suggested that rodents may lack one of the isoforms (L-form). This study solved this issue, as a nucleotide substitution occurred at a splice donor site followed by a large deletion in the rodent genome compared with human, which made the generation of the L-form impossible. This study also revealed overlapping of the IRSp53 and AATK genes coded for by complementary strands.

Membrane targeting of WAVE2 is not sufficient for WAVE2-dependent actin polymerization: a role for IRSp53 in mediating the interaction between Rac and WAVE2

“…S1B). Moreover, we confirmed the presence of three other murine IRSp53 family members (splice variants), described previously (Miyahara et al, 2003), in macrophages (supplementary material Fig. S1C).…”

The interplay between Eps8 and IRSp53 contributes to Src-mediated transformation

“…IRSp53 is critical in Src-mediated transformation P-S Liu et al (that is, mIRSp53S, mIRSp53T and mIRSp58M) with different C-terminal amino-acid residues (Miyahara et al, 2003) were reported in murine cells. As insulin increased the phosphorylation of IRSp53S and IRSp53L, insulin-like growth factor I augmented the phosphorylation of IRSp53T (Okamura-Oho et al, 2001).…”

“…IRSp53, also known as brain-specific angiogenesis inhibitor 1-associated protein 2 (Abbott et al, 1999;Oda et al, 1999), is a founding member of a newly discovered family of proteins, including missing-in-metastasis (MIM) and actin-bundling protein with brain-specific angiogenesis inhibitor 1-associated protein 2 homology (Scita et al, 2008). In addition to the originally identified 53-kDa protein IRSp53 (designated IRSp53S from now on), there are at least three other human isoforms (designated IRSp58M, IRSp53T and IRSp53L) have been identified whereas only three murine homologues (that is, mIRSp53S, mIRSp58M and mIRSp53T) have been detected (Miyahara et al, 2003). Interestingly, IRSp53S is suggested to be a candidate disease sensor of neurodegenerative polyglutamine (polyQ) expression (OkamuraOho et al, 1999).…”

Frequent occurrence of protein isoforms with or without a single amino acid residue by subtle alternative splicing: the case of Gln in DRPLA affects subcellular localization of the products

“…Other cases of protein isoforms with or without a single amino acid residue During the course of the above experiments, we experienced other cases of inclusion or exclusion of 3 nt in a cloning process of GHRHR encoding the growth hormone releasing hormone receptor (Miki et al 1996) and also in the determination of exon-intron boundaries for BAIAP2 encoding IRSp53 Miyahara et al 2003). Literature surveys detected a few previous reports that clearly depicted isoforms with a subtle difference due to alternative splicing utilizing two acceptor sites separated by 3 nt (Manrow and Berger 1993;Condorelli et al 1994;Vogan et al 1996;Oberkofler et al 1997;Lin et al 2000; from PTMA to Dnmt1 in Table 1).…”