title: Charge effects modulate actin assembly by classic myelin basic protein isoforms.
abstract: Myelin basic protein (MBP), a highly cationic structural protein of the myelin sheath, is believed to be associated with the cytoskeleton in vivo and interacts with actin in vitro, but little is known about the regulation of this interaction. The rate and extent of actin polymerization induced by 18.5 kDa MBP charge isomers were correlated to charge reduction by post-translational modifications. Increased ionic strength attenuated the initial rate but not the final extent of polymerization achieved. Reduced pH enhanced the rate and extent of polymerization, presumably via partial protonation of intrinsic histidyl residues. The polymerizing activities of the 21.5, 17, and 14 kDa MBP splice variants were not proportionate to their net charges or charge densities. The presence of at least one region derived from exon II or VI of the "classic" MBP gene was required for effective bundling as assessed by light scattering and transmission electron microscopy.
authors.affiliation: Department of Molecular and Cellular Biology, Biophysics Interdepartmental Group, University of Guelph, Guelph, Ont., Canada N1G 2W1.
authors.forename: Christopher M D
authors.initials: CM
authors.lastname: Hill
authors.forename: George
authors.initials: G
authors.lastname: Harauz
mesh_terms: D000199:Actins / Q000737:chemistry*; D017398:Alternative Splicing; D000818:Animals; D001669:Biochemical Phenomena; D001671:Biochemistry; D002118:Calcium / Q000737:chemistry; D002147:Calmodulin / Q000737:chemistry; D002417:Cattle; D003599:Cytoskeleton / Q000378:metabolism; D005091:Exons; D017353:Gene Deletion; D006863:Hydrogen-Ion Concentration; D007477:Ions; D008027:Light; D051379:Mice; D046529:Microscopy, Electron, Transmission; D004676:Myelin Basic Protein / Q000737:chemistry*; D009836:Oligodendroglia / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D011189:Potassium Chloride / Q000737:chemistry; D011485:Protein Binding; D020033:Protein Isoforms; D011499:Protein Processing, Post-Translational; D011817:Rabbits; D012542:Scattering, Radiation; D013997:Time Factors
chemical_list: D000199:Actins; D002147:Calmodulin; D007477:Ions; D004676:Myelin Basic Protein; D011108:Polymers; D020033:Protein Isoforms; D011189:Potassium Chloride; D002118:Calcium