The myosin light chain kinase gene is not duplicated in mouse: Partial structure and chromosomal localization of Mylk

The gene encoding myosin light chain kinase (MYLK) is duplicated on human c hromosome 3 (HSA3; 3p13;3q21) and on a chromosome with conserved synteny to HSA3 in most non-human primate species. In human, the functional copy resi des on 3q21, whereas the 3p13 site contains a pseudogene. To trace the orig in of the duplication, we characterized the mouse gene Mylk. A single seque nce corresponding to the functional Mylk was detected. We sequenced a 180-k b bacterial artificial chromosome clone containing the 24 first exons of My lk; the complete mouse gene is expected to span >200 kb. Comparisons with t he draft of the human genome revealed that the sequence and structure of MY LK are conserved in mammals. Fluorescence in situ hybridization (FISH) anal ysis indicated that the mouse gene localizes to a single site on chromosome 16B4-B5, a region with conserved synteny with HSA3q. Our study provides in formation on both the structure and the evolution of MYLK in mammals and su ggests that it was duplicated after the divergence of rodents and primates.