| Literature References | 1. ATTWOOD, T.K. AND FINDLAY, J.B.C.
Fingerprinting G protein-coupled receptors.
PROTEIN ENG. 7(2) 195-203 (1994).
2. ATTWOOD, T.K. AND FINDLAY, J.B.C.
G protein-coupled receptor fingerprints.
7TM, VOLUME 2, EDS. G.VRIEND AND B.BYWATER (1993).
3. BIRNBAUMER, L.
G proteins in signal transduction.
ANNU.REV.PHARMACOL.TOXICOL. 30 675-705 (1990).
4. CASEY, P.J. AND GILMAN, A.G.
G protein involvement in receptor-effector coupling.
J.BIOL.CHEM. 263(6) 2577-2580 (1988).
5. ATTWOOD, T.K. AND FINDLAY, J.B.C.
Design of a discriminating fingerprint for G protein-coupled receptors.
PROTEIN ENG. 6(2) 167-176 (1993).
6. GRANDY, D.K., MARCHIONNI, M.A., MAKAM, H., STOFKO, R.E., ALFANO, M.,
FROTHINGHAM, L., FISCHER, J.B., BURKE-HOWIE, K.J., BUNZOW, J.R.,
SERVER, A.C. AND CIVELLI, O.
Cloning of the cDNA and gene for a human D2 dopamine receptor.
PROC.NATL.ACAD.SCI.U.S.A. 86 9762-9766 (1989).
7. WATSON, S. AND ARKINSTALL, S.
Dopamine.
IN THE G PROTEIN-LINKED RECEPTOR FACTSBOOK, ACADEMIC PRESS, pp96-110.
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| Documentation | G protein-coupled receptors (GPCRs) constitute a vast protein family that
encompasses a wide range of functions (including various autocrine, para-
crine and endocrine processes). They show considerable diversity at the
sequence level, on the basis of which they can be separated into distinct
groups. We use the term clan to describe the GPCRs, as they embrace a group
of families for which there are indications of evolutionary relationship,
but between which there is no statistically significant similarity in
sequence [1]. The currently known clan members include the rhodopsin-like
GPCRs, the secretin-like GPCRs, the cAMP receptors, the fungal mating
pheromone receptors, and the metabotropic glutamate receptor family.
The rhodopsin-like GPCRs themselves represent a widespread protein family
that includes hormone, neurotransmitter and light receptors, all of
which transduce extracellular signals through interaction with guanine
nucleotide-binding (G) proteins. Although their activating ligands vary
widely in structure and character, the amino acid sequences of the
receptors are very similar and are believed to adopt a common structural
framework comprising 7 transmembrane (TM) helices [3-5].
Dopamine neurons in the vertebrate central nervous system are involved in
the initiation and execution of movement, the maintenance of emotional
stability, and the regulation of pituitary function [6]. Various human
neurological diseases (e.g., Parkinson disease and schizophrenia), are
believed to be manifestations of dopamine and dopamine receptor imbalance.
The receptors have been divided into several different subtypes (designated
D1-D5), which may be distinguished by their G protein coupling, ligand
specificity, anatomical distribution and physiological effects.
D3 receptors have a similar pharmacological profile to D2 receptors. They
are expressed predominantly in the limbic area (including the olfactory
tubercle, nucleus accumbens, islands of Calleja and hypothalamus), and they
are present in lower levels in the caudate-putamen and cerebral cortex [7].
The receptors are also found in dopamine cell bodies in the substantia
nigra [7]. The distribution of the receptors is consistent with a role in
cognition and emotional functions; they may thus be the target of anti-
psychotic therapy involving dopamine antagonists [7].
DOPAMINED3R is a 7-element fingerprint that provides a signature for the
D3 family of dopamine receptors. The fingerprint was derived from an initial
alignment of 6 sequences: the motifs were drawn from conserved sections
within either loop or N-terminal regions, focusing on those areas of the
alignment that characterise the D3 receptors but distinguish them from the
rest of the rhodopsin-like superfamily - motif 1 lies at the N-terminus;
motif 2 spans the second cytoplasmic loop, leading into the N-terminus of
TM domain 4; motifs 3-6 span the third cytoplasmic loop; and motif 7 spans
the third external loop, leading into the N-terminus of TM domain 7. A
single iteration on OWL28.1 was required to reach convergence, no further
sequences being identified beyond the starting set. Two partial matches
were also found, A48258 and A55419, both of which are D3 receptor fragments.
An update on SPTR37_9f identified a true set of 5 sequences.
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