Myosin light chain compositions of the interatrial and interventricular septa of sheep heart

Summary The myosin light chain composition of sheep interatrial and interventricular septa were analysed by one- and two-dimensional polyacrylamide gel. The interventricular septum has myosin light chain composition indistinguishable from that of ventricular myosin. Myosin from the interatrial septum contains three light chains, two of which co-migrated with the two atrial light chains (ALC₁ and ALC₂), while the third co-migrated with ventricular light chain 2 (VLC₂). ALC₁ are more abundant than ALC₂ or VLC₂ suggesting a mixed myosin population. Myosin with ALC₁ and VLC₂ light chain composition may be present, and its possible relationship with cardiac conducting cells is discussed.