ALTERNATIVE SPLICING AND STRUCTURE OF THE HUMAN AND MOUSE SFRS5 HRS/SRP40 GENES/

HRS/SRp40/SFRS5 (HRS) is an SR (serine-arginine-rich) protein which re gulates both alternative splicing and basal splicing. HRS mRNA contain s several transcripts, including HRS-SF and HRS-LF which have differen t temporal patterns of expression in proliferating liver. As previousl y reported, HRS-SF mRNA encodes the SR splicing factor. However, the i dentity of HRS-LF remained unknown. Here, we cloned and characterized the mouse HRS gene, partial human HRS gene, and several cDNAs derived from HRS-LF mRNA. The mouse HRS gene spans 5050 bp and contains eight exons and seven introns HRS-LF mRNA contains a 1.2 kb insert within th e SF mRNA with stop codons in all three reading frames. A comparison o f HRS-LF and the HRS gene revealed that HRS-LF mRNA is an intron-retai ning product which contains intron 5. At most, HRS-LF encodes a trunca ted HRS protein with one RNA binding domain. Interestingly, intron 5 d emonstrates 90% identity between the mouse and human HRS genes, implyi ng that intron 5 might play an important role in regulating HRS gene s plicing or expression. (C) 1997 Elsevier Science B.V.