TY - JOUR
T1 - Identification of Src Phosphorylation Sites in the Catenin p120 ctn
AU - Mariner, Deborah J.
AU - Anastasiadis, Panos
AU - Keilhack, Heike
AU - Böhmer, Frank D.
AU - Wang, Jue
AU - Reynolds, Albert B.
PY - 2001/7/27
Y1 - 2001/7/27
N2 - p120-catenin (p120ctn) interacts with the cytoplasmic tail of cadherins and is thought to regulate cadherin clustering during formation of adherens junctions. Several observations suggest that p120 can both positively and negatively regulate cadherin adhesiveness depending on signals that so far remain unidentified. Although p120 tyrosine phosphorylation is a leading candidate, the role of this modification in normal and Src-transformed cells remains unknown. Here, as a first step toward pinpointing this role, we have employed two-dimensional tryptic mapping to directly identify the major sites of Src-induced p120 phosphorylation. Eight sites were identified by direct mutation of candidate tyrosines to phenylalanine and elimination of the accompanying spots on the two-dimensional maps. Identical sites were observed in vitro and in vivo, strongly suggesting that the physiologically important sites have been correctly identified. Changing all of these sites to phenylalanine resulted in a p120 mutant, p120-8F, that could not be efficiently phosphorylated by Src and failed to interact with SHP-1, a tyrosine phosphatase shown previously to interact selectively with tyrosine-phosphorylated p120 in cells stimulated with epidermal growth factor. Using selected tyrosine to phenylalanine p120 mutants as dominant negative reagents, it may now be possible to selectively block events postulated to be dependent on p120 tyrosine phosphorylation.
AB - p120-catenin (p120ctn) interacts with the cytoplasmic tail of cadherins and is thought to regulate cadherin clustering during formation of adherens junctions. Several observations suggest that p120 can both positively and negatively regulate cadherin adhesiveness depending on signals that so far remain unidentified. Although p120 tyrosine phosphorylation is a leading candidate, the role of this modification in normal and Src-transformed cells remains unknown. Here, as a first step toward pinpointing this role, we have employed two-dimensional tryptic mapping to directly identify the major sites of Src-induced p120 phosphorylation. Eight sites were identified by direct mutation of candidate tyrosines to phenylalanine and elimination of the accompanying spots on the two-dimensional maps. Identical sites were observed in vitro and in vivo, strongly suggesting that the physiologically important sites have been correctly identified. Changing all of these sites to phenylalanine resulted in a p120 mutant, p120-8F, that could not be efficiently phosphorylated by Src and failed to interact with SHP-1, a tyrosine phosphatase shown previously to interact selectively with tyrosine-phosphorylated p120 in cells stimulated with epidermal growth factor. Using selected tyrosine to phenylalanine p120 mutants as dominant negative reagents, it may now be possible to selectively block events postulated to be dependent on p120 tyrosine phosphorylation.
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U2 - 10.1074/jbc.M102443200
DO - 10.1074/jbc.M102443200
M3 - Article
C2 - 11382764
AN - SCOPUS:0035958886
SN - 0021-9258
VL - 276
SP - 28006
EP - 28013
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 30
ER -