Human serine/threonine protein kinase EMK1: Genomic structure and cDNA cloning of isoforms produced by alternative splicing

The EMK (ELKL, Motif Kinase) is a small family of ser/thr protein kinases involved in the control of cell polarity, microtubule stability and cancer. We have isolated several cDNA clones that encoded two isoforms of the human ser/thr protein kinase EMK1 (GDB symbol EMK1, alias ELKL motif kinase 1, and MARK2). These isoforms were characterized by the presence of a 162-bp alternative exon that gave rise to two forms, one containing the exon and the other one lacking it. Both forms were found to be coexpressed in a number of selected cell lines and tissue samples when analyzed by RT-PCR. By Northern blot, human EMK1 was shown to be encoded by a single mRNA ubiquitously expressed. We have reconstructed most of the genomic structure of EMK1 from the sequence of two human chromosome 11 cosmids deposited in databases, and showed that the gene is composed of a minimum of 16 small exons.