EXPRESSION OF ACTIN ISOFORMS IN THE GUINEA-PIG ORGAN OF CORTI - MUSCLE ISOFORMS ARE NOT DETECTED

The specificity of antibodies to actin was assayed by use of immunoblo ts and histological sections of control tissues enriched for each of s ix different isoforms. On immunoblots, all antibodies stained at most one band of protein in most of the control materials, with a molecular weight of approximately 43 kDa. Their pattern of staining of muscle a nd nonmuscle tissues indicated their isoform specificity. On tissue se ctions, immunocytochemical staining demonstrated cellular and subcellu lar localization of the different isoforms. Once characterized with re gard to specificity, these antibodies were used to probe actin in the guinea pig organ of Corti. None of the four muscle isoforms of actin w ere found in either immunoblots or tissue sections of the organ of Cor ti. Both beta- and gamma-cytoplasmic isoforms of actin were present in hair cells and supporting cells. This leaves open to investigation th e role which cytoplasmic actins play in these cells of the organ of Co rti.