A 270-KDA POLYPEPTIDE FROM MUNG BEAN SHARES MULTIPLE EPITOPES WITH RABBIT SKELETAL MYOSIN AND BINDS ADP-AGAROSE

A 170 kDa polypeptide that has been partially purified from mung beans is retained by ADP-agarose even in the absence of divalent cations wh en most non-myosin ATPases and kinases do not bind. Attempts to demons trate a myosin-like ATPase activity were inconclusive, however, and th e protein accounts at most for only a small part of the total K(+)EDTA ATPase activity of mung bean extracts. All four monoclonal antibodies raised to the 170 kDa polypeptide react with rabbit skeletal muscle m yosin and localize the 170 kDa polypeptide in mung bean root tip cells to the actin-containing phragmoplast and to sites dispersed throughou t the cytoplasm which probably include some but not all actin cables. These 4 monoclonals and 3 commercially available antimyosin monoclonal s all recognise rabbit skeletal myosin and 160-170 kDa proteins that a re present in two other angiosperms tested. In addition, a 158 kDa pro tein of mung bean reacts with only one antibody and does not bind ADP- agarose. We conclude that strong but not yet conclusive evidence point s to the 160-170 kDa proteins of angiosperms being a widely conserved for ln of myosin heavy chain.