2',3'-CYCLIC NUCLEOTIDE 3'-PHOSPHODIESTERASE BINDS TO ACTIN-BASED CYTOSKELETAL ELEMENTS IN AN ISOPRENYLATION-INDEPENDENT MANNER

2',3'-Cyclic nucleotide 3'-phosphodiesterase (CNP) is an isoprenylated protein enriched in myelin and oligodendrocytes but also present in s everal other tissues at low levels. CNP binds avidly to membranes and in addition possesses several characteristics of cytoskeletal proteins . The role of isoprenylation in the association of CNP with the cytosk eleton was analyzed by ectopic expression in L cells of epitope-tagged CNP1 and a non-isoprenylated mutant CNP1. Using nonionic detergent ex traction, drug-mediated cytoskeletal disruption, and coimmunoprecipita tion with an anti-actin antibody, we show that CNP1 is associated with actin-based cytoskeletal elements independently of its isoprenylation status. A control protein, p21c-H-ras, which is also modified by isop renylation at its carboxyl-terminus, does not bind to cytoskeletal str uctures as judged by the same criteria. We present a model that accoun ts for the association of CNP1 with membranes and the cytoskeleton.