Identification and Isolation of Actin from Neurospora crassa

Abstract

Crude cell extracts of N. crassa contained an abundant protein that was identified as actin by a number of criteria. The protein, in cell extracts or in pure form, co-migrated with rabbit skeletal muscle actin in polyacrylamide gels. The N. crassa actin was purified by DEAE-cellulose and DNAase I-Sepharose chromatography and had the expected property of inhibiting DNAase I activity. Although N. crassa actin could polymerize and depolymerize, purification based entirely on this characteristic was ineffective. The action was susceptible to proteolytic degradation and under certain conditions, a breakdown product of defined size was observed.