B-50/GAP-43 Binds to Actin Filaments Without Affecting Actin Polymerization and Filament Organization |
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Authors: | Jacques J H Hens Fabio Benfenati† Henk B Nielander‡ Flavia Valtorta§ Willem Hendnk Gispen Pierre N E De Graan |
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Institution: | Department of Medical Pharmacology, Rudolf Magnus Institute, University of Utrecht, Utrecht, The Nelherlands;Institute of Human Physiology, University of Modena, Modena, Roma;Department of Experimental Medicine, II University of Roma, Roma;Department of Medical Pharmacology, Rudolf Magnus Institute, University of Utrecht, Utrecht, The Nelherlands;"Bruno Ceccarelli" Center for the Study of Peripheral Neuropathies, Department oj Medical Pharmacology, National Research Council Center of Cytopharmacology, San Raffaele Scientific Institute, University of Milano, Milano, Italy |
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Abstract: | Abstract: To investigate a possible function of the nervous tissuespecific protein kinase C substrate B-50/GAP-43 in regulati of the dynamics of the submembranous cytoskeleton. we studii the interaction between purified 6–50 and actin. Both the phosphorylated and dephosphorylated forms of 8–50 cosedi-mented with filamentous actin (F-actin) in a Ca2+-independent manner. Neither 6–50 nor phospho-6–50 had any effect on the kinetics of actin polymerization and on the critical concentration at steady state, as measured using pyrenylated actin. tight scattering of F-actin samples was not increased in the presence of 550, suggesting that 550 does not bundle actin filaments. The number of actin filaments, determined by 3H]cytochalasin B binding, was not affected by either phospho- or dephospho-B-50, indicating that 550 has neither a severing nor a capping effect. These observations were confirmed by electron microscopic evaluation of negatively stained F-actin samples, which did not reveal any structural changes in the actin meshwork on addition of 6–50, We conclude that 6–50 is an actin-binding protein that does not directly affect actin dynamics. |
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Keywords: | B-50/GAP-43 -Actin Cytaskeleton Actin-kictin-binding proteins Protein kinase C |
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