Use of immobilized lactoperoxidase to label L cell proteins involved in adhesion to polystyrene.

Abstract

Proteins involved in the attachment of murine [neoplastic fibroblasts] L cells to polystyrene were identified by a technique designed to iodinate only those macromolecules coming into closest apposition to the substratum. Whereas soluble lactoperoxidase (LPO) catalyzes the radioiodination of a broad spectrum of polypeptides, the same enzyme immobilized on polystyrene tissue culture flasks discriminately labels 55,000 and 42,000 MW polypeptides that adhere tightly to the substratum after the cells are removed. One-dimensional peptide mapping following limited proteolysis showed that the labeled 55,000 MW polypeptide is simildr to a component of comparable MW present in the detergent-extracted cytoskeleton. The functional association of 2 cytoskeletal structures, presumably 10 nm filaments and actin, is discussed, and alternative explanations for their susceptibility to iodination by immobilized LPO are presented.