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:
“One of the most highly valued functions of used parents these days is to be the villains of their children’s lives, the people the child blames for any shortcomings or disappointments. But if your identity comes from your parents’ failings, then you remain forever a member of the child generation, stuck and unable to move on to an adulthood in which you identify yourself in terms of what you do, not what has been done to you.”
—Frank Pittman (20th century)
“When Western people train the mind, the focus is generally on the left hemisphere of the cortex, which is the portion of the brain that is concerned with words and numbers. We enhance the logical, bounded, linear functions of the mind. In the East, exercises of this sort are for the purpose of getting in tune with the unconscious—to get rid of boundaries, not to create them.”
—Edward T. Hall (b. 1914)
“Mark the babe
Not long accustomed to this breathing world;
One that hath barely learned to shape a smile,
Though yet irrational of soul, to grasp
With tiny finger—to let fall a tear;
And, as the heavy cloud of sleep dissolves,
To stretch his limbs, bemocking, as might seem,
The outward functions of intelligent man.”
—William Wordsworth (1770–1850)