Isolation and characterization of cDNA clones for human skeletal muscle α actin

Abstract

Two cDNA libraries corresponding to polyA ⁺ RNA from human adult skeletal muscle have been constructed by cloning 1n the PstI site of pBR322. Skeletal a actin cDNA clones have been Isolated and characterized. Three of these plasmids have overlapping Inserts which together contain the complete 5' non-coding and protein-coding region and part of the 3' untranslated region. Determination of the sequence of the cloned cDNA confirms the complete conservation 1n human of the am1no–ac1d sequence of skeletal a actin compared to the rabbit or rat proteins. The 5– untranslated region, but not the 3– untranslated region, shows good homology with the corresponding one 1n the rat gene. Analysis of changes at silent sites within the protein–coding region suggests that the divergence of skeletal and cardiac a actin took place much earlier than the mammalian radiation. The plasmids described here have been used as probes to detect the homologous gene among the about thirty actin sequences present 1n the human genome.