RESUMO
The glycine-rich G loop controls ATP binding and phosphate transfer in protein kinases. Here we show that the functions of Src family and Abl protein tyrosine kinases require an electrostatic interaction between oppositely charged amino acids within their G loops that is conserved in multiple other phylogenetically distinct protein kinases, from plants to humans. By limiting G loop flexibility, it controls ATP binding, catalysis, and inhibition by ATP-competitive compounds such as Imatinib. In WeeB mice, mutational disruption of the interaction results in expression of a Lyn protein with reduced catalytic activity, and in perturbed B cell receptor signaling. Like Lyn(-/-) mice, WeeB mice show profound defects in B cell development and function and succumb to autoimmune glomerulonephritis. This demonstrates the physiological importance of the conserved G loop salt bridge and at the same time distinguishes the in vivo requirement for the Lyn kinase activity from other potential functions of the protein.
Assuntos
Biocatálise , Sequência Conservada , Proteínas Quinases/química , Eletricidade Estática , Quinases da Família src/química , Quinases da Família src/metabolismo , Sequência de Aminoácidos , Animais , Doenças Autoimunes/imunologia , Doenças Autoimunes/patologia , Linfócitos B/citologia , Linfócitos B/efeitos dos fármacos , Linfócitos B/enzimologia , Benzamidas , Biocatálise/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos , Ativação Enzimática/efeitos dos fármacos , Proteínas de Fusão bcr-abl/metabolismo , Mesilato de Imatinib , Camundongos , Camundongos Mutantes , Dados de Sequência Molecular , Mutação/genética , Filogenia , Piperazinas/farmacologia , Estabilidade Proteica/efeitos dos fármacos , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Pirimidinas/farmacologia , Receptores de Antígenos de Linfócitos B/metabolismo , Transdução de Sinais/efeitos dos fármacosRESUMO
OBJECTIVES: To investigate the cause of a persistent test strip error code, error 2b, appearing on LifeScan SureStep Flexx glucose meters (Johnson and Johnson, Rochester, USA). DESIGN AND METHODS: SaniCloth Plus (The Dynarex Corporation, Orangeburg, USA), CaviWipes XL (Metrex, Orange, USA), and Accel (HANSA Med Ltd., Mississauga, Canada) sanitizing agents were tested in an attempt to reproduce the error. RESULTS: The error 2b code was encountered when the Accel was used as a cleaning agent, but not when SaniCloth Plus or CaviWipes XL were used. CONCLUSIONS: The hydrogen peroxide contained in Accel (HANSAmed, Ltd., Mississauga, Canada) interferes with the glucose oxidase reaction on the test strip, causing the error 2b code.