A new family of genes and pseudogenes potentially expressing testis- and brain-specific leucine zipper proteins in man and mouse

We have characterized a new mouse gene highly transcribed in the testis, an d a derived intronless gene expressed in the embryo. The latter gene is pre sent in Mus musculus domesticus and in Mus musculus castaneus but is absent in Mus spretus. The sequencing of different clones from a testis cDNA libr ary reveals a complex transcriptional regulation for the intron-containing gene. The use of several promoters, alternative splicing and trans-splicing , and of two different polyadenylation sites account for the diversity. The different cDNAs encode proteins with features of basic helix-loop-helix le ucine zipper (bHLH-ZIP) DNA-binding factors with homology to a new brain-sp ecific factor. The presence of multiple CK2 and PKC phosphorylation sites s uggests that their activity may be regulated by phosphorylation. In man, a pseudogene, apparently derived from the same transcript as in mouse and sho wing 90% homology in the coding region, is present within an intron of anot her gene. Interestingly, although the human pseudogene is highly mutated in human, in the mouse it has only four nucleotide changes compared with the cDNA of origin, and is still capable of encoding a protein. (C) 2000 Elsevi er Science B.V. All rights reserved.