Functions
A variety of specific physiological functions have been attributed to the sigma-1 receptor. Chief among these are modulation of Ca2+ release, modulation of cardiac myocyte contractility, and inhibition of voltage gated K+ channels. The reasons for these effects are not well understood, even though sigma-1 receptors have been linked circumstantially to a wide variety of signal transduction pathways. Links between sigma-1 receptors and G-proteins have been suggested such as sigma-1 receptor antagonists showing GTP-sensitive high affinity binding, there is also, however, some evidence against a G-protein coupled hypothesis. The sigma-1 receptor has been shown to appear in a complex with voltage gated K+ channels (Kv1.4 and Kv1.5), leading to the idea that sigma-1 receptors are auxiliary subunits. Sigma-1 receptors apparently co-localize with IP3 receptors on the endoplasmic reticulum. Also, sigma-1 receptors have been shown to appear in galactoceramide enriched domains at the endoplasmic reticulum of mature oligodendrocytes. The wide scope and effect of ligand binding on sigma-1 receptors has led some to believe that sigma-1 receptors are intracellular signal transduction amplifiers.
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Famous quotes containing the word functions:
“Let us stop being afraid. Of our own thoughts, our own minds. Of madness, our own or others. Stop being afraid of the mind itself, its astonishing functions and fandangos, its complications and simplifications, the wonderful operation of its machinerymore wonderful because it is not machinery at all or predictable.”
—Kate Millett (b. 1934)
“The mind is a finer body, and resumes its functions of feeding, digesting, absorbing, excluding, and generating, in a new and ethereal element. Here, in the brain, is all the process of alimentation repeated, in the acquiring, comparing, digesting, and assimilating of experience. Here again is the mystery of generation repeated.”
—Ralph Waldo Emerson (18031882)
“Empirical science is apt to cloud the sight, and, by the very knowledge of functions and processes, to bereave the student of the manly contemplation of the whole.”
—Ralph Waldo Emerson (18031882)