Article Abstract:
Research on the mitogen-activated protein kinase (MAPK) signalling cascade indicates that tyrosine kinase Syk is essential for the Gi-coupled pathway, while both Syk and the Src-related tyrosine kinase Lyn are needed for the Gq-coupled pathway. Simulation by Gq-coupled m1 muscarinic acetylcholine receptors of MAPK kinase and MAPK is inhibited in cells lacking the Src-associated tyrosine kinase Lyn. Structural domains SH2, SH3 and kinase domains in both Lyn and Syk tyrosine kinases play a major role in signal transmission.
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Article Abstract:
Researchers investigated the stimulation of protein-tyrosine kinases by guanine-nucleotide-binding regulatory proteins (G proteins). The malfunction of protein-tyrosine kinases, which are cellular signal transducers, frequently causes cancer. The researchers used purified G-protein subunits and non-receptor tyrosine kinases in a reconstitution study and demonstrated that the alpha-subunit of the Gq class of G protein directly activates Bruton's tyrosine kinase. The mechanism of activation is unclear.
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Article Abstract:
Signal transducer heterotrimeric guanine-nucelotide-binding proteins (G proteins), relay messages from receptors on the cell surface to control certain cellular processes. Galpha12 is shown to bind directly to and stimulate activity of Bruton's tyrosine kinase and a Ras GTPase-activating protein Gap1m. It interacts with a conserved domain and this is thought to be the first study to identify direct effectors for Galpha12.
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