Differential expression of two skeletal muscle betatropomyosin mRNAs during Xenopus laevis development

Abstract

A cDNA clone for a Xenopus laevis skeletal muscle β-tropomyosin (β- TMad) isoform was isolated from an adult skeletal muscle cDNA library. Sequence analysis revealed that this clone corresponded to a second β- tropomyosin mRNA distinct from the one that was previously characterized (β- TMemb). The two skeletal β-TM mRNAs originate from distinct genes and are differentially expressed during development. β-TMemb mRNA is expressed only in the somites of the early embryo while β-TMad mRNA is expressed in pre- metamorphic tadpoles and adult skeletal muscles. We have isolated the promoter region of the β-TMemb gene and shown that a DNA construct containing 2.9 kb of promoter region is properly expressed after injection in the embryo.