Actin and myosin during pollen germination

Actin and myosin from pollen tubes ofLilium davidii were studied by using imrnunoblotting, Dot-Blot and myosin Ca²⁺ -ATPase analysis. On immunoblotting of the total soluble pollen tube proteins, anti-α-actin antibody labelled a polypeptide approximately 43 ku, which is considered to be the actin of lily. The mRNA encoding actin in ungerminated pollen and germinated pollen were both undetectable in our experiments. A myosin exhibited Ca²⁺ -ATPase activity, with a native molecular weight of 460 ku has been identified by using immunoblotting. A polypeptide of about 205 ku and a polypeptide of about 20 ku were the heavy chain and a set of light chain of the myosin, which can crossreact with anti-skeletal muscle myosin heavy chain monoclonal antibody and anti-skeletal muscle myosin light chain (20 ku) monoclonal antibody, respectively. The Ca²⁺-ATPase activities of myosin in crude extracts of germinated pollen were pitively related to the growth rates of pollen tubes.