Characterization of a rat myosin alkali light chain gene expressed in ventricular and slow twitch skeletal muscles

Abstract

Mammalian cardiac muscle contains two myosin alkali light chains: 1) the atrial light chain (MLClA), and 2) the ventricular light chain (MLClV) predominantly expressed either in the atrium or in the ventricle. In this report we describe the isolation and characterization of the complete gene for rat MLClV. The rat MLClV gene is ∼6.5 kb long and the mRNA coding sequences are organized in 7 different exons. Comparison of this gene sequence with other known MLCl gene sequences revealed that the exon-intron organization is highly conserved within the MLCl gene family. The derived protein sequence of rat MLClV showed a higher sequence homology with human ventricular (96%) MLClV than with rat fast skeletal MLClf (74%), suggesting functional similarities between different MLClV proteins. S1 nuclease mapping and primer extension analysis demonstrated that this gene is expressed only in ventricular and slow twitch skeletal muscle tissues and is transcribed from the same promoter and transcription initiation site. © 1989 IRL Press at Oxford University Press.