title: Transitions in human atrial and ventricular myosin light-chain isoenzymes in response to cardiac-pressure-overload-induced hypertrophy.
abstract: 1. The light-chain subunits of human atrial and ventricular cardiac muscle were examined by two-dimensional polyacrylamide-gel electrophoresis and limited proteolytic digestion. The light-chain patterns in the normal right and left atria were identical. 2. Myosin preparations isolated from right or left atria that had been subjected to cardiac-pressure-overload-induced hypertrophy also contained ventricular light-chain subunits. These were identified by peptide mapping in sodium dodecyl sulphate. 3. Ventricular light chain-2 was the major species in hypertrophied atria, although light chain-1 subsequently appeared in severe pressure-overload-hypertrophied cases. Evidence is presented for the existence of more than one form of ventricular light chain-2. 4. The transition from atrial to ventricular myosin light chains correlated with the degree of pressure-overload hypertrophy in 83 examples of surgically excised atria. 5. The adult atrial light chain-1 was shown to be homologous to the human foetal ventricular light chain-1 [Price, Littler & Cummins (1980) Biochem. J. 191, 571-580] by peptide mapping. 6. A scheme of atrial/ventricular myosin light-chain isoenzyme transitions is discussed in relation to changing contractile properties in cardiac muscle, together with implications for the role of light-chain subunits.
mesh_terms: D001794:Blood Pressure; D006332:Cardiomegaly / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006325:Heart Atria / Q000378:metabolism; D006352:Heart Ventricles / Q000378:metabolism; D006801:Humans; D007525:Isoelectric Focusing; D007527:Isoenzymes / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism*; D010446:Peptide Fragments / Q000032:analysis
chemical_list: D007527:Isoenzymes; D010446:Peptide Fragments; D009218:Myosins