title: Ubiquitination of red blood cell alpha-spectrin does not affect heterodimer formation.
abstract: Erythrocyte alpha-spectrin is ubiquitinated in repeats alpha20/alpha21, which also represents the nucleation site for contact with the beta subunit which leads to heterodimer formation by a zippering mechanism. In this study we have determined the second-order rate constant for association of ubiquitinated alpha'-spectrin, nonubiquitinated alpha-spectrin, and beta-spectrin into the alpha'beta or alphabeta heterodimer. The rate constant for incorporation of monomers into heterodimers at 37 degrees C were (5.181 +/- 0.001) x 10(5) M(-1) sec(-1) for total alpha-spectrin (alpha + alpha'), (5.121 +/- 0.001) x 10(5) M(-1) sec(-1) for alpha'-spectrin, and (5.178 +/- 0.003) x 10(5) M(-1) sec(-1) for beta-spectrin. We conclude that ubiquitination of alpha-spectrin does not regulate heterodimer formation.
authors.affiliation: Department of Molecular and Cell Biology, University of Texas at Dallas, Richardson, Texas 75083-0688, USA.
authors.forename: Mahnoush H
authors.initials: MH
authors.lastname: Riahi
authors.forename: David G
authors.initials: DG
authors.lastname: Kakhniashvili
authors.forename: Steven R
authors.initials: SR
authors.lastname: Goodman
mesh_terms: D000755:Anemia, Sickle Cell / Q000097:blood / Q000235:genetics; D019281:Dimerization; D004912:Erythrocytes / Q000378:metabolism*; D006720:Homozygote; D006801:Humans; D007700:Kinetics; D013049:Spectrin / Q000378:metabolism*; D025801:Ubiquitin / Q000097:blood*
chemical_list: D025801:Ubiquitin; D013049:Spectrin