PubMed:7831290 JSONTXT

{"project":"AIMed","denotations":[{"id":"T1","span":{"begin":29,"end":35},"obj":"protein"},{"id":"T2","span":{"begin":74,"end":77},"obj":"protein"},{"id":"T3","span":{"begin":78,"end":83},"obj":"protein"},{"id":"T4","span":{"begin":90,"end":112},"obj":"protein"},{"id":"T5","span":{"begin":149,"end":152},"obj":"protein"},{"id":"T6","span":{"begin":176,"end":179},"obj":"protein"},{"id":"T7","span":{"begin":180,"end":185},"obj":"protein"},{"id":"T8","span":{"begin":187,"end":190},"obj":"protein"},{"id":"T9","span":{"begin":275,"end":278},"obj":"protein"},{"id":"T10","span":{"begin":283,"end":286},"obj":"protein"},{"id":"T11","span":{"begin":335,"end":338},"obj":"protein"},{"id":"T12","span":{"begin":343,"end":346},"obj":"protein"},{"id":"T13","span":{"begin":425,"end":428},"obj":"protein"},{"id":"T14","span":{"begin":433,"end":436},"obj":"protein"},{"id":"T15","span":{"begin":505,"end":508},"obj":"protein"},{"id":"T16","span":{"begin":509,"end":512},"obj":"protein"},{"id":"T17","span":{"begin":588,"end":591},"obj":"protein"},{"id":"T18","span":{"begin":592,"end":595},"obj":"protein"},{"id":"T19","span":{"begin":663,"end":666},"obj":"protein"},{"id":"T20","span":{"begin":721,"end":724},"obj":"protein"},{"id":"T21","span":{"begin":793,"end":796},"obj":"protein"},{"id":"T22","span":{"begin":994,"end":997},"obj":"protein"},{"id":"T23","span":{"begin":1073,"end":1078},"obj":"protein"},{"id":"T24","span":{"begin":1170,"end":1193},"obj":"protein"},{"id":"T25","span":{"begin":1195,"end":1206},"obj":"protein"},{"id":"T26","span":{"begin":1286,"end":1297},"obj":"protein"},{"id":"T27","span":{"begin":1301,"end":1304},"obj":"protein"},{"id":"T28","span":{"begin":1383,"end":1394},"obj":"protein"},{"id":"T29","span":{"begin":1409,"end":1412},"obj":"protein"},{"id":"T30","span":{"begin":1424,"end":1429},"obj":"protein"},{"id":"T31","span":{"begin":1457,"end":1462},"obj":"protein"},{"id":"T32","span":{"begin":1491,"end":1494},"obj":"protein"},{"id":"T33","span":{"begin":1499,"end":1510},"obj":"protein"}],"text":"Human spleen tyrosine kinase p72Syk associates with the Src-family kinase p53/56Lyn and a 120-kDa phosphoprotein.\nThe 72-kDa spleen tyrosine kinase (Syk) and Src-family kinase p53/56Lyn (Lyn) contribute to signaling via the B-cell antigen receptor complex. Here we show that Syk and Lyn from human B lymphocytes can interact directly. Syk and Lyn coimmunoprecipitated from mature and activated B-cell lines, and gel-purified Syk and Lyn reassociated in vitro, demonstrating their direct interaction. This Syk-Lyn interaction may be dependent on the stage of B-cell differentiation, since Syk-Lyn associations were not detected in pre-B and myeloma cell lines and Syk from an immature B-cell line did not reassociate with Lyn in vitro. Serine/threonine kinase activity was also associated with Syk. Crosslinking of cell surface IgM led to rapid activation of both tyrosine and serine/threonine protein kinase activities that resulted in phosphorylation in vitro of proteins coprecipitating with Syk--in particular, a serine/threonine phosphorylated protein 120 kDa in size (pp120). Several phosphoproteins, including one of 72 kDa and one of 120 kDa, coprecipitated with phospholipase C-gamma 1 (PLC gamma 1). Sequential immunoprecipitation identified the 72-kDa protein associated with PLC gamma 1 as Syk. The 120-kDa serine/threonine phosphorylated protein that coprecipitated with PLC gamma 1 resembled the Syk-associated pp120 by several criteria. Thus, pp120 may serve as a link between Syk and PLC gamma 1, coupling the B-cell antigen receptor to the phosphatidylinositol pathway."}