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6 Cards in this Set

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What is a common way to translate a signal to a biological effect inside cells?
It is by way of nucleotide regulatory proteins(G proteins) that bind GTP.
What is GTP?
It is the guanosine analog of ATP. When the signal reaches a G protein, the protein exchanges GDP for GTP. The GTP protein brings about the effect. The inherent GTPase activity of the protein then converts GTP to GDP, restoring the resting state.
What are heterotrimeric G proteins?
They couple cell surface receptors to catalytic units that catalyze the intracellular formation of second messengers or couple the receptors directly to ion channels.
These heterotrimeric proteins are made up of 3 subunits, designated, a, b, and y(alpha, beta and gamma. TRUE/FALSE
TRUE. When a ligand binds to a G coupled receptor, this GDP is exchanged for GTP, and the alpha subunit separates from the combined beta and gamma subunits. This separated alpha subunit brings about many biological effects. The beta and gamma subunits do not separate, and the combined beta-gamma(by) activate other effectors. The intrinsic GTPase activity of the alpha subunit then converts GTP to GDP, and this leads to reassociation of the alpha with the beta-gamma subunit and termination of effector activation.
What is the difference between 1st and 2nd messengers?
many ligands in the ECF bind to receptors on the surface of cells, and many of them trigger the release of intracellular mediators such as cAMP, IP3 and DAG, that initiate changes in cell function. The extracellular ligands are first messengers, and the intracellular mediators are second messengers.
Many G proteins are modified by having specific lipids attached to them, i.e. they are lipidated. TRUE/FALSE
TRUE. Trimeric G proteins may be myristolated, palmitoylated or prenylated. Small proteins may be prenylated.