The cyclic nucleotides cAMP and cGMP are implicated in signal transduction events such as the visual transduction, relaxation of smooth muscles, intestinal secretion of water and salt, reabsorption of Na+ and water in the distal tubule of the nephrons.
cAMP/cGMP activate Ca2+ -permeable ion channels called cyclic nucleotide-gated channels (CNG or CNC).
Activation of CNG leads to depolarization of the membrane voltage and to a concomitant increase of the cytosolic Ca2+.
CNG consists of two distinct subunits, designated a and b subunits.
Several CNG a-subunits (CNG alpha 1-3) & beta subunits (subunit 2 or CNGb1-2 or CNG4-5) and numerous isoforms.
a-subunit can form functional channel by themselves, whereas, b-subunits modulate the channel property of a-subunits.
CNG display intracellular N and C-termini, 6 transmembrane domains or segments (S1-S6).
The region between S5 and S6 contains the ion-conducting pore (P).
The cyclic nucleotide-binding region is found at the c-terminus.
Native functional CNG may exists as heteromultimer containing some combination of a, and b subunits.
CNG beta-subunit or subunit 2 (also called CNG4) have been cloned from the rod outer segments (hRCNC2a and hRCNC2b) and from olfactory neurons (rOCNC2, also called CNG5).
Human RCNC2a (623 aa; missing 1-286 aa) and RCNC2b (909 aa) are alternatively splice and only differ in their N-terminus.
The two b proteins show ~30% identity with human a CNG1.
Additional alternatively spliced CNG4D (missing 522-530 aa) and CNG4E (missing 515-532 aa) are also expressed.
CNG b-subunits form heterooligomeric complex with CNG1-3.
The olfactory b-subunit is expressed throughout the nasal epithelium, especially in olfactory sensory neurons, and in the vomeronasal organ
Applications:Suitable for use in ELISA.
Western Blot, though not tested, may potentially be used as an application.
