Significance Of Receptor Subtypes

Molecular cloning has accelerated discovery of novel receptor subtypes, and their expression as recombinant proteins has facilitated discovery of subtype-selective drugs. Distinct but related receptors may, but may not, display distinctive patterns of selectivity among agonist or antagonist ligands. When selective ligands are not known, the receptors are more commonly referred to as isoforms rather than as subtypes. The distinction between classes and subtypes of receptors, however, often is arbitrary or historical. The a, aT and j receptors differ from each other both in ligand selectivity among drugs and in coupling to G proteins (Gq, G,, and Gs, respectively), yet a and j are considered receptor classes and a, and a2 are considered subtypes. The a^, a,B, and a1C receptor isoforms differ little in their biochemical properties, although their tissue distributions are distinct. The j,, P2, and fi3 adrenergic receptor subtypes exhibit both differences in tissue distribution and phosphorylation by either GRKs or PKA.

Pharmacological differences among receptor subtypes are exploited therapeutically through the development and use of receptor-selective drugs. Such drugs may be used to elicit different responses from a single tissue when receptor subtypes initiate different intracellular signals, or they may serve to differentially modulate different cells or tissues that express one or another receptor subtype. Increasing the selectivity of a drug among tissues or among responses elicited from a single tissue may determine whether the drug's therapeutic benefits outweigh its unwanted effects.

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Diabetes 2

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Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...

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