What is TRPC
TRPC is a family of transient receptor potential cation channels in animals.
TRPC channels form the subfamily of channels in human most closely related to drosophila TRP channels. Structurally, this family shares a number of similar characteristics. At the proximal C-terminus of this sub-family is a TRP box motif containing the invariant EWKFAR sequence and between 3 and 4 ankyrin repeats near the N-terminus. These channels are non-selectively permeable to cations, with a selectivity of calcium over sodium variable among the different members. Many of TRPC channel subunits are able to coassemble.[1]
In general, TRPC channels can be activated by phospholipase C stimulation, with some members also activated by diacylglycerol. There is one at least one report that TRPC1 is also activated by stretching of the membrane and TRPC5 channels are activated by extracellular reduced thioredoxin. [2]
It has long been proposed that TRPC channels underlie the store-operated channels (SOC) observed in many cell types. These channels open due to the depletion of intracellular calcium stores. Two other proteins, stromal interaction molecules (STIMs) and the ORAIs, however, have more recently been implicated in this process. It should be noted that STIM1 and TRPC1 can coassemble, complicating the understanding of this phenomenon.[1]
TRPC6 and TRPC4 have been implicated in late onset Alzheimer’s disease.[3][4][5]
Tags: Integral membrane proteins, Ion channels, Membrane proteins, Proteins, Transmembrane proteins
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In addition to activating PKC, diacylglycerol has a number of other functions in the cell:
a source for prostaglandins
a precursor of the endocannabinoid 2-arachidonoylglycerol
an activator of a subfamily of TRPC (Transient Receptor Potential Canonical) cation channels, TRPC
Transient receptor potential cation channel, subfamily C, member 5, also known as TRPC5, is subtype of the TRPC family of mammalian transient receptor potential ion channels. Homomultimeric TRPC5 and heteromultimeric TRPC5-TRPC1 channels are activated by extracellular reduced thioredoxin [1]. This activation probably plays a role in rheumatoid arthritis.
TRPM is a family of transient receptor potential ion channels where the "M" stands for "melastatin".[1] Functional TRPM channels are believed to form tetramers.[2]
Unlike the TRPC and TRPV sub-families, TRPM subunits do not contain N-terminal ankyrin repeat motifs but, rather, contain entire functional proteins in their C-termini. TRPM6 and TRPM7, for example, contain functional ?-kinase segments, which are a type of serine/threonine-specific protein kinase.
There are other types of ion channel classifications that are based on less normal characteristics, e.g. multiple pores and transient potentials.
Almost all ion channels have one single pore. However, there are also those with two:
Two-pore channels: This small family of 2 members putatively forms cation-selective ion channels. They are predicted to contain two KV-style six-transmembrane domains, suggesting they form a dimer in the membrane. These channels are related to catsper channels channels and, more distantly, TRP channels.
There are channels that are classified by the duration of the response to stimuli:
Transient receptor potential channels: This group of channels, normally referred to
Voltage-gated channels open and close in response to membrane potential.
Voltage-gated sodium channels: This family contains at least 9 members and is largely responsible for action potential creation and propagation. The pore-forming ? subunits are very large (up to 4,000 amino acids) and consist of four homologous repeat domains (I-IV) each comprising six transmembrane segments (S1-S6) for a total of 24 transmembrane segments. The members of this family also coassemble with auxiliary ? subunits, each spanning the membrane once. Both ? and ? subunits are extensively glycosylated.
Voltage-gated calcium channels: This family contains 10 members, though these members are known to coassemble
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