Evidence for isoforms of the phosphorylatable myosin light chain in rat uterus

The phosphorylatable myosin light chain of rat uterus was resolved into four spots by two-dimensional gel electrophoresis. Antibody against the 20 kDa light chain from smooth muscle myosin recognized these four spots. Purified light chain exhibited four spots on a diagonal upon isoelectrofocusing in both first and second dimensions, proving that these spots are not due to artifactual charge modification. Accordingly, the four spots contain light chain isoforms derived from myosin.