title: Phosphotyrosine-dependent targeting of mitogen-activated protein kinase in differentiated contractile vascular cells.
abstract: Tyrosine phosphorylation has been linked to plasmalemmal targeting of src homology-2-containing proteins, activation of mitogen-activated protein (MAP) kinase, nuclear signaling, and proliferation of cultured cells. Significant tyrosine phosphorylation and MAP kinase activities have also been reported in differentiated cells, but the signaling role of tyrosine-phosphorylated MAP kinase in these cells is unclear. The spatial and temporal relation between phosphotyrosine and MAP kinase immunoreactivity was quantified in differentiated contractile vascular smooth muscle cells by using digital imaging microscopy. An initial association of MAP kinase with the plasmalemma required upstream protein kinase C activity but occurred in a tyrosine phosphorylation-independent manner. Subsequent to membrane association, a delayed redistribution of MAP kinase, colocalizing with the actin-binding protein caldesmon, occurred in a tyrosine phosphorylation-dependent manner. The apparent association of MAP kinase with the contractile proteins coincided with contractile activation. Thus, tyrosine phosphorylation appears to target MAP kinase to cytoskeletal proteins in contractile vascular cells. This targeting mechanism may determine the specific destination and thereby the specialized function of MAP kinase in other phenotypes.
authors.affiliation: Program in Smooth Muscle Research, Harvard Medical School, Boston, MA, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: Khalil
authors.forename: C B
authors.initials: CB
authors.lastname: Menice
authors.forename: C L
authors.initials: CL
authors.lastname: Wang
authors.forename: K G
authors.initials: KG
authors.lastname: Morgan
mesh_terms: D000818:Animals; D001011:Aorta / Q000166:cytology; D002148:Calmodulin-Binding Proteins / Q000378:metabolism; D002469:Cell Separation; D005289:Ferrets; D005455:Fluorescent Antibody Technique; D007091:Image Processing, Computer-Assisted; D015151:Immunoblotting; D008853:Microscopy / Q000379:methods; D019950:Mitogen-Activated Protein Kinase 1; D009119:Muscle Contraction; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism; D010656:Phenylephrine / Q000494:pharmacology; D010766:Phosphorylation; D019000:Phosphotyrosine; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D017346:Protein Serine-Threonine Kinases / Q000032:analysis / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011994:Recombinant Proteins / Q000032:analysis / Q000378:metabolism*; D015398:Signal Transduction; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000032:analysis / Q000378:metabolism
chemical_list: D002148:Calmodulin-Binding Proteins; D011994:Recombinant Proteins; D010656:Phenylephrine; D019000:Phosphotyrosine; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D019950:Mitogen-Activated Protein Kinase 1