title: Molecular interaction of S-100 proteins with microtubule proteins in vitro.
abstract: Several procedures were employed to examine the in vitro interaction between S-100 proteins and microtubule proteins. Binding of S-100 to tau factors was observed under all experimental conditions. S-100 binding to microtubule-associated protein 2 (MAP2) was best detected by exposing nitrocellulose-immobilized MAP2 or MAPs to either 125I-labeled S-100 or biotinylated S-100. S-100 binding to tubulin was detected when the two protein fractions were first incubated with each other followed by exposure to the bifunctional cross-linker disuccinimidylsuberate, and then separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and transfered onto nitrocellulose paper. By this procedure, complex formation between S-100 and tubulin, as well as between S-100 and a relatively low-molecular-weight MAP, was evidenced by immunoblotting using an anti-S-100 antiserum. Alternatively, complex formation between biotinylated S-100 and either tubulin or MAPs was visualized by means of avidin-peroxidase, after SDS-PAGE of the complex mixtures and transfer of the separated proteins onto nitrocellulose. The interaction between S-100 and tubulin was strictly Ca2+ dependent, and resistant to high concentrations of KCl, colchicine, or vinblastine.
authors.affiliation: Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Donato
authors.forename: I
authors.initials: I
authors.lastname: Giambanco
authors.forename: M C
authors.initials: MC
authors.lastname: Aisa
mesh_terms: D000818:Animals; D003432:Cross-Linking Reagents; D004347:Drug Interactions; D006652:Histological Techniques; D008868:Microtubule Proteins / Q000378:metabolism*; D051381:Rats; D009418:S100 Proteins / Q000378:metabolism*; D013388:Succinimides
chemical_list: D003432:Cross-Linking Reagents; D008868:Microtubule Proteins; D009418:S100 Proteins; D013388:Succinimides; C019358:disuccinimidyl suberate