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- ***********************************************
- * Cyclic nucleotide-binding domain signatures *
- ***********************************************
-
- Proteins that bind cyclic nucleotides (cAMP or cGMP) share a structural domain
- of about 120 residues [1-3]. The best studied of these proteins is the
- prokaryotic catabolite gene activator (also known as the cAMP receptor
- protein) (gene crp) where such a domain is known to be composed of three
- alpha-helices and a distinctive eight-stranded, antiparallel beta-barrel
- structure. Such a domain is known to exist in the following proteins:
-
- - Prokaryotic catabolite gene activator protein (CAP).
- - cAMP- and cGMP-dependent protein kinases (cAPK and cGPK). Both types of
- kinases contains two tandem copies of the cyclic nucleotide-binding domain.
- The cAPK's are composed of two different subunits: a catalytic chain and a
- regulatory chain which contains both copies of the domain. The cGPK's are
- single chain enzymes that include the two copies of the domain in their N-
- terminal section. The nucleotide specificity of cAPK and cGPK is due to an
- amino acid in the conserved region of beta-barrel 7: a threonine that is
- invariant in cGPK is an alanine in most cAPK.
- - Vertebrate cyclic nucleotide-gated ion-channels. Two such cations channels
- have been fully characterized. One is found in rod cells where it plays a
- role in visual signal transduction. It specifically binds to cGMP leading
- to an opening of the channel and thereby causing a hyperpolarization of rod
- neurons. In olfactory epithelium a similar, cAMP-binding, channel plays a
- role in odorant signal transduction.
-
- There are six invariant amino acids in this domain, three of which are glycine
- residues that are thought to be essential for maintenance of the structural
- integrity of the beta-barrel. We developed two signature patterns for this
- domain. The first pattern is located within beta-barrels 2 and 3 and contains
- the first two conserved Gly. The second pattern is located within beta-
- barrels 6 and 7 and contains the third conserved Gly as well as the three
- other invariant residues.
-
- -Consensus pattern: [LIVM]-[VIC]-x(2)-G-[DENQTA]-x-[GA]-x(2)-[LIVMFY](4)-x(2)-
- G
- -Sequences known to belong to this class detected by the pattern: ALL.
- -Other sequence(s) detected in SWISS-PROT: NONE.
-
- -Consensus pattern: [LIVMF]-G-E-x-[GAS]-[LIVM]-x(5,11)-R-[STAQ]-A-x-[LIVMA]-x-
- [STACV]
- -Sequences known to belong to this class detected by the pattern: ALL.
- -Other sequence(s) detected in SWISS-PROT: Xanthomonas campestris xanB.
-
- -Last update: October 1993 / First entry.
-
- [ 1] Weber I.T., Shabb J.B., Corbin J.D.
- Biochemistry 28:6122-6127(1989).
- [ 2] Kaupp U.B.
- Trends Neurosci. 14:150-157(1991).
- [ 3] Shabb J.B., Corbin J.D.
- J. Biol. Chem. 267:5723-5726(1992).
-