Murine cortactin is phosphorylated in response to fibroblast growth factor-1 on tyrosine residues late in the G1 phase of the BALB/c 3T3 cell cycle.
We have previously reported that BALB/c 3T3 cells require a prolonged exposure to fibroblast growth factor (FGF)-1 for the stimulation of maximal DNA synthesis, and this event correlates with the tyrosine phosphorylation of novel proteins late in G1 including a protein termed p80/p85 (Zhan, X., Hu, X., Friesel, R., and Maciag, T. (1993) J. Biol. Chem. 268, 9611-9620). We have purified, sequenced, and cloned the cDNA encoding p80/p85 and report that it is the murine homolog of the chicken cortactin gene and a member of the human hematopoietic specific-1 gene family. Immunochemical analysis of m-cortactin-tyrosine phosphorylation in response to FGF-1 demonstrates a biphasic phosphorylation pattern both as a weak immediate-early and strong mid to late G1 response protein. Because the chicken cortactin gene was originally isolated as a substrate for v-Src, FGF-1 may influence the enzymatic activity of other cell-associated tyrosine kinases which utilize p80/p85 (cortactin) as a polypeptide substrate.
Zhan
X
X
Department of Molecular Biology, Holland Laboratory, American Red Cross, Rockville, Maryland 20855.
Hu
X
X
Hampton
B
B
Burgess
W H
WH
Friesel
R
R
Maciag
T
T
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D051356:Cortactin; D016220:Fibroblast Growth Factor 1 / Q000378:metabolism*; D016193:G1 Phase; D051379:Mice; D008807:Mice, Inbred BALB C; D008840:Microfilament Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D010766:Phosphorylation; D014443:Tyrosine / Q000378:metabolism*
D051356:Cortactin; C495869:Cttn protein, mouse; D008840:Microfilament Proteins; D009838:Oligodeoxyribonucleotides; D016220:Fibroblast Growth Factor 1; D014443:Tyrosine