ANALYSIS OF CDNAS ENCODING DROSOPHILA-MELANOGASTER MYOSIN LIGHT-CHAINKINASE

Myosin Light chain kinase regulates the activity of myosin by phosphor ylating the myosin regulatory light chain. Here we describe the clonin g and characterization of cDNAs encoding Drosophila melanogaster myosi n light chain kinase. We amplified a fragment of the Drosophila mlck g ene using degenerate primers homologous to a highly conserved region i n myosin light chain kinase proteins of vertebrate species. We used th e gene fragment to isolate corresponding Drosophila mlck cDNAs. The de duced protein sequence of the cDNAs shows high homology to the catalyt ic and regulatory domains of vertebrate nonmuscle, smooth muscle and s keletal muscle myosin light chain kinase. Protein motifs I and II, whi ch are present in vertebrate nonmuscle and smooth muscle myosin light chain kinase, but not in skeletal muscle myosin light chain kinase, ar e also present in Drosophila myosin light chain kinase. Transcript and cDNA analysis shows the gene encodes multiple messages and is express ed in nonmuscle and muscle cells, including the adult indirect flight muscle. Genomic Southern analysis and chromosome hybridization suggest mlck is a single copy gene which maps to chromosome band 52D, and is not haplo-insufficient for flight.