Phosphotyrosine-containing proteins are concentrated in focal adhesions and intercellular junctions in normal cells.

AUTOR(ES)

Maher, P A

RESUMO

We have used a high-affinity polyclonal antibody directed against phosphotyrosine (P-Tyr) to localize P-Tyr-containing proteins in normal and transformed cells in culture by immunofluorescence microscopy experiments. The distribution of the proteins with modified tyrosine was compared with that of F-actin in these cells. Cells infected with Abelson murine leukemia virus were found to contain elevated levels of P-Tyr, as expected. Various permanent lines of fibroblastic and epithelial cells exhibited lower, but easily detectable, levels of P-Tyr. The P-Tyr in fibroblasts was concentrated at the focal contacts at the termini of actin-containing microfilament bundles and, in the epithelial cells examined, at the intercellular junctions. Early passages of primary cultures of chicken embryo fibroblasts and chicken embryo heart cells also showed detectable levels of P-Tyr in focal contacts and cell-cell junctions. However, P-Tyr was not detectable in later passages of chicken embryo fibroblasts. The concentration of P-Tyr-containing proteins in intercellular junctions in normal cells suggests that these are sites of significant biochemical regulatory activities which may be important in the control of normal cell adhesivity, motility, and shape.

Documentos Relacionados

• Phosphotyrosine-containing lactate dehydrogenase is restricted to the nuclei of PC12 pheochromocytoma cells.
• Detection of phosphotyrosine-containing proteins in polyomavirus middle tumor antigen-transformed cells after treatment with a phosphotyrosine phosphatase inhibitor.
• Identification of Phosphotyrosine-Containing Proteins in Untransformed and Rous Sarcoma Virus-Transformed Chicken Embryo Fibroblasts
• Phosphotyrosine-containing proteins and expression of transformation parameters in cells infected with partial transformation mutants of Rous sarcoma virus.
• Association of the v-crk oncogene product with phosphotyrosine-containing proteins and protein kinase activity.