The nature and function of alamethicin.

The tubulin-rich fraction was also shown to contain a protein subunit, of mol.wt. 46000f 1500, identified as actin by co-electrophoresis with skeletal-muscle actin. Although actin can be removed from brain tubulin preparations by repeated cycles of depolymerization/polymerization, its total removal from the platelet tubulin-rich fraction is most difEcult. In addition to tubulin and actin, three higher-molecular-weight components are apparent (Fig. l), some of whichmay represent the dynein-like proteinsrecently observed in brain tubulin preparations obtained by polymerization (Gaskin e ta / . , 1974; Burns & Pollard, 1974).