Identification of two novel mammalian genes establishes a subfamily of KH-domain RNA-binding proteins

We have identified two novel human genes encoding proteins with a high level of sequence identity to two previously characterized RNA-binding proteins, alpha CP-1 and alpha CP-2, Both of these novel genes, alpha CP-3 and alpha CP-4, are predicted to encode proteins with triplicated KH domains. The number and organization of the KH domains, their sequences, and the sequences of the contiguous regions are conserved among all four alpha CP proteins. The common evolutionary origin of these proteins Is substantiated by conservation of exon-intron organization in the corresponding genes. The map positions of alpha CP-1 and alpha CP-2 (previously reported) and those of alpha CP-3 and alpha CP-4 (present report) reveal that the four alpha CP loci are dispersed in the human genome; alpha CP-3 and alpha CP-4 mapped to 21q22.3 and 3p21, and the respective mouse orthologues mapped to syntenic regions of the mouse genome, 10B5 and 9F1F2, respectively. Two additional loci in the human genome were identified as alpha CP-2 processed pseudogenes (PCBP2P1, 21q22.3, and PCBP2P2, 8q21-q22). Although the overall levels of alpha CP-3 and alpha CP-4 mRNAs are substantially lower than those of alpha CP-1 and alpha CP-2, transcripts of alpha CP-3 and alpha CP-4 were found in all mouse tissues tested. These data establish a new subfamily of genes predicted to encode closely related KH-containing RNA-binding proteins with potential functions in posttranscriptional controls. (C) 2000 Academic Press.