Regulatory mechanisms of a chemoattractant receptor on human polymorphonuclear leukocytes.
The oligopeptide chemotactic factor receptor in leukocyte membranes exists in two affinity states that are in part interconvertible. Convertibility is regulated by guanine nucleotides, which suggests that a nucleotide regulatory unit allosterically modifies receptor affinity and participates in its transduction mechanisms. Approximately one-third of the high-affinity receptors in polymorphonuclear leukocyte (PMN) membranes are not subject to guanine nucleotide regulation. This fraction can be increased by agonist preincubation and could represent an intermediate form of the receptor prior to signal transduction and/or internalization. Pharmacologic manipulation of viable PMNs demonstrates that the affinity and functional activity of the chemoattractant receptor can be altered divergently by aliphatic alcohols and polyene antibiotics. The alcohols raise the receptors' affinity, enhance chemotaxis, but markedly depress chemoattractant-induced secretory mechanisms. In contrast, polyene antibiotics lower the receptors' affinity, depress chemotaxis, but enhance specific granule secretion. Thus, a relationship exists between the chemoattractant receptors' affinity and their ability to transduce signals for either chemotaxis or secretion.
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