Synaptic Signaling And The Dopamine D4 Receptor
The human D4 dopamine receptor is a synaptic neurotransmitter
receptor responsible for neuronal signaling in the mesolimbic
system of the brain, a part of the brain that regulates
emotion and complex behavior. It is a particularly interesting
GPCR because a large number of polymorphic variants of the
receptor gene exist in the human population. The gene varies
in the nucleotide sequence of the region encoding the
intracellular polypeptide loop that links transmembrane segments
5 and 6. This loop, known as i3, may contain from 2 to 7 or
more similar 48 base pair repeats (see figure below). The
different nucleotide repeats code for more than 18 different
hexadecapeptide sequences. The role of loop i3 in receptor
function is not known.
This particularly proline-rich sequence in loop i3 is unique
to the D4 dopamine receptor. We are interested in elucidating
the role of this region of the receptor in its function as a
synaptic neurotransmitter receptor.
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