Identification of the phosphorylated beta-tubulin isotype in differentiated neuroblastoma cells.
The tubulin molecule consists of an alpha- and a beta-subunit, each of which exists in several isotypic forms. It has been previously shown that one of the isotypes of neuroblastoma beta-tubulin is phosphorylated at a serine residue in vivo [(1985) J. Cell Biol. 100, 764-774]. Here we identify the phosphorylated isotype as beta 2 (type III). Moreover, the large size of the phosphorylated tryptic peptide and sequence comparisons of vertebrate beta-tubulins suggest that one of the two serines in positions 444 and 446 is the phosphorylated residue. Our results raise the possibility that beta 2-tubulin differs functionally from the other beta-tubulin isotypes.
Ludueña
R F
RF
Department of Biochemistry, University of Texas, San Antonio 78284.
Zimmermann
H P
HP
Little
M
M
D002454:Cell Differentiation; D004591:Electrophoresis, Polyacrylamide Gel; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology; D010446:Peptide Fragments / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D010446:Peptide Fragments; D010710:Phosphates; D014404:Tubulin; D010768:Phosphoserine; D011494:Protein Kinases; D014357:Trypsin