Characterization of rat brain stathmin isoforms by two-dimensional gel electrophoresis matrix assisted laser desorption/ionization and electrospray ionization ion trap mass spectrometry

Zugaro, LM; Reid, GE; Ji, H; Eddes, JS; Murphy, AC; Burgess, AW; Simpson, RJ

Author(s): Zugaro, LM; Reid, GE; Ji, H; Eddes, JS; Murphy, AC; Burgess, AW; Simpson, RJ;
Details: Publication Year 1998-05,Volume 19,Issue #5,Page 867-876
Journal Title: ELECTROPHORESIS
Publication Type: Journal Article
Abstract: Stathmin is a regulatory phosphoprotein that is a target for both cell cycle and cell surface receptor-regulated phosphorylation events. There are at least 14 isoforms of stathmin that migrate on two-dimensional electrophoresis (2-DE): two unphosphorylated, and 12 increasingly phosphorylated proteins. Following extracellular stimuli, stathmin is phosphorylated on four serines (Ser16, Ser25, Ser38, and Ser63) by several kinases, such as mitogen-activated protein (MAP), cdc2 kinase, protein kinase A, and Ca2+/calmodulin-dependent kinase-Gr. While all forms of stathmin are derived from the same protein encoded by a single mRNA, the precise nature of the post-translational modifications has not been clear. In this study we have characterized three rat brain stathmin isoforms, #1, #3 and #4, which electrophorese on 2-DE with apparent molecular weight (M-r)/isoelectric point (pI) values of 15500/6.2, 15000/6.1, and 15000/6.0, respectively. The phosphorylation status of these isoforms was determined using a combination of peptide mapping, matrix-assisted laser desorption/ionization mass spectrometry and electrospray-ionization ion trap mass spectrometry. Stathmin isoform #1 was not phosphorylated, stathmin isoform #3 was phosphorylated on Ser38 only, and stathmin isoform #4 was phosphorylated on Ser38; however, the phosphorylation status of Ser63 could not be determined. In addition, three proteins which electrophorese near stathmin were identified in order to more accurately define the M-r/pI locus of this region of the 2-DE gel map. These include: phosphatidyl ethanolamine binding protein (M-r similar to 18000/pI 6.0), synuclein forms 2 and 3 (M-r similar to 14000/pI 5.4), and synuclein form 2 (M-r similar to 15000/pI 5.0).
Publisher: WILEY-V C H VERLAG GMBH
Keywords: CYCLE-REGULATED PHOSPHORYLATION; NEURON-ENRICHED PHOSPHOPROTEIN; MULTIPLE SIGNAL-TRANSDUCTION; PROTEIN-KINASE; SERINE PHOSPHORYLATION; IDENTIFICATION; CELLS; ONCOPROTEIN-18; PEPTIDE; DIFFERENTIATION
Publisher's Version: https://doi.org/10.1002/elps.1150190544
Terms of Use/Rights Notice: Refer to copyright notice on published article.

Creation Date: 1998-05-01 12:00:00