| Literature References | 1. LINDER, M.E. AND GILMAN, A.G.
G proteins.
SCI.AM. 70-77 (1993).
2. KAZIRO, Y., ITOH, H., KOZASA, T., NAKAFUKU, M. AND SATOH, T.
Structure and function of signal-transducing GTP-binding proteins.
ANNU.REV.BIOCHEMISTRY 60 349-400 (1991).
3. SIMON, M.I., STRATHMANN, M.P. AND GAUTAM, N.
Diversity of G proteins in signal transduction.
SCIENCE 252 802-808 (1993).
4. CLAPHAM, D.E. AND NEER, E.J.
New roles for G protein beta-gamma dimers in transmembrane signalling.
NATURE 365 403-406 (1993)
5. LUPAS, A.N., LUPAS, J.M. AND STOCK, J.B.
Do G protein subunits associate via a 3-stranded coiled coil?
FEBS LETT. 314 105-108 (1992).
6. DURONIO, R.J., GORDON, J.I. AND BOGUSKI, M.S.
Comparative analysis of the beta-transducin family with identification of
several new members including pwp1, a non-essential gene of Saccharomyces
cerevisiae that is divergently transcribed from nmt1.
PROTEINS 13(1) 41-56 (1992).
7. VAN DER VOORN, L. AND PLOEGH, H.L.
The WD-40 repeat.
FEBS LETT. 307(2) 131-134 (1992).
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| Documentation | Guanine nucleotide binding proteins (G proteins) are a family of membrane-
associated proteins that couple extracellularly-activated integral-membrane
receptors to intracellular effectors, such as ion channels and enzymes that
vary the concentration of second messenger molecules [1-3]. G proteins are
composed of 3 subunits (alpha, beta and gamma) which, in the resting state,
associate as a trimer at the inner face of the plasma membrane. The alpha
subunit has a molecule of guanosine diphosphate (GDP) bound to it:
stimulation of the G protein by an activated receptor leads to its exchange
for GTP (guanosine triphosphate). This results in the separation of the
alpha from the beta and gamma subunits, which always remain tightly
associated as a dimer. Both the alpha and beta-gamma subunits are then able
to interact with effectors, either individually or in a cooperative manner.
The intrinsic GTPase activity of the alpha subunit hydrolyses the bound GTP
to GDP. This returns the alpha subunit to its inactive conformation and
allows it to reassociate with the beta-gamma subunit, thus restoring the
system to its resting state.
Although originally thought to be a passive attenuator and membrane anchor
for the activated alpha subunit, the beta-gamma subunit is now recognised
as playing an active role in a number of different G protein-coupled
signalling events [4]. It has been shown to modulate the activity of some
isoforms of adenylyl cyclase, phospholipase C, and some ion channels. It is
involved in receptor phosphorylation via specific kinases, and has been
implicated in the p21ras-dependent activation of the MAP kinase cascade.
It is also highly likely that it contributes to the recognition of specific
receptors by the G protein. No atomic structure is yet available for beta-
gamma subunits, but it has been proposed that they interact both with each
other and with other proteins via a coiled coil motif in their N-terminal
regions [5].
Four different G protein beta subunits have been identified in mammals,
and some have also been identified in certain invertebrate species. Beta
subunits contain around 340 amino acids, with apparent molecular weights
of 35-36 kDa. Their sequences are highly conserved between species,
implying that they perform a fundamentally important role in the
organisation of G protein linked systems [6]. The sequences display tandem
repeats of a 40-residue domain containing a characteristic Trp-Asp motif
(the so-called WD-40 repeat [7]).
GPROTEINB is a 4-element fingerprint that provides a signature for the
G-beta subunits. The fingerprint was derived from an initial alignment of
6 sequences: the motifs were drawn from conserved regions within the first
two-thirds of the alignment, motif 2 including part of a WD-40 repeat. Two
iterations on OWL21.1 were required to reach convergence, at which point a
true set comprising 12 sequences was identified. Three partial matches were
also found, including 2 G-beta-like proteins and murine nedd-1 protein,
which is known to share partial similarity with the G-beta subunits.
An update on SPTR37_9f identified a true set of 33 sequences, and 1
partial match.
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| Sequence Titles | GBB1_CAEEL GUANINE NUCLEOTIDE-BINDING PROTEIN BETA SUBUNIT 1 - CAENORHABDITIS ELEGANS.
GBB1_DROME GUANINE NUCLEOTIDE-BINDING PROTEIN BETA SUBUNIT 1 - DROSOPHILA MELANOGASTER (FRUIT FLY).
GBB1_HOMAM GUANINE NUCLEOTIDE-BINDING PROTEIN G(I)/G(S)/G(T) BETA SUBUNIT 1 (TRANSDUCIN BETA CHAIN 1) - HOMARUS AMERICANUS (AMERICAN LOBSTER).
GBB1_HUMAN GUANINE NUCLEOTIDE-BINDING PROTEIN G(I)/G(S)/G(T) BETA SUBUNIT 1 (TRANSDUCIN BETA CHAIN 1) - HOMO SAPIENS (HUMAN), MUS MUSCULUS (MOUSE), BOS TAURUS (BOVINE), AND CANIS FAMILIARIS (DOG).
GBB1_RAT GUANINE NUCLEOTIDE-BINDING PROTEIN G(I)/G(S)/G(T) BETA SUBUNIT 1 (TRANSDUCIN BETA CHAIN 1) - RATTUS NORVEGICUS (RAT).
GBB1_TOBAC GUANINE NUCLEOTIDE-BINDING PROTEIN BETA SUBUNIT 1 - NICOTIANA TABACUM (COMMON TOBACCO).
GBB1_XENLA GUANINE NUCLEOTIDE-BINDING PROTEIN G(I)/G(S)/G(T) BETA SUBUNIT 1 (TRANSDUCIN BETA CHAIN 1) (XGBETA1) - XENOPUS LAEVIS (AFRICAN CLAWED FROG).
GBB2_DROME GUANINE NUCLEOTIDE-BINDING PROTEIN BETA SUBUNIT 2 - DROSOPHILA MELANOGASTER (FRUIT FLY).
GBB2_HUMAN GUANINE NUCLEOTIDE-BINDING PROTEIN G(I)/G(S)/G(T) BETA SUBUNIT 2 (TRANSDUCIN BETA CHAIN 2) - HOMO SAPIENS (HUMAN).
GBB2_MOUSE GUANINE NUCLEOTIDE-BINDING PROTEIN G(I)/G(S)/G(T) BETA SUBUNIT 2 (TRANSDUCIN BETA CHAIN 2) - MUS MUSCULUS (MOUSE).
GBB2_RAT GUANINE NUCLEOTIDE-BINDING PROTEIN G(I)/G(S)/G(T) BETA SUBUNIT 2 (TRANSDUCIN BETA CHAIN 2) - RATTUS NORVEGICUS (RAT).
GBB2_TOBAC GUANINE NUCLEOTIDE-BINDING PROTEIN BETA SUBUNIT 2 - NICOTIANA TABACUM (COMMON TOBACCO).
GBB3_CANFA GUANINE NUCLEOTIDE-BINDING PROTEIN G(I)/G(S)/G(T) BETA SUBUNIT 3 (TRANSDUCIN BETA CHAIN 3) - CANIS FAMILIARIS (DOG).
GBB3_HUMAN GUANINE NUCLEOTIDE-BINDING PROTEIN G(I)/G(S)/G(T) BETA SUBUNIT 3 (TRANSDUCIN BETA CHAIN 3) - HOMO SAPIENS (HUMAN).
GBB3_RAT GUANINE NUCLEOTIDE-BINDING PROTEIN G(I)/G(S)/G(T) BETA SUBUNIT 3 (TRANSDUCIN BETA CHAIN 3) - RATTUS NORVEGICUS (RAT).
GBB3_TOBAC GUANINE NUCLEOTIDE-BINDING PROTEIN BETA SUBUNIT - NICOTIANA TABACUM (COMMON TOBACCO).
GBB4_MOUSE GUANINE NUCLEOTIDE-BINDING PROTEIN BETA SUBUNIT 4 (TRANSDUCIN BETA CHAIN 4) - MUS MUSCULUS (MOUSE).
GBB5_CAEEL GUANINE NUCLEOTIDE-BINDING PROTEIN BETA SUBUNIT 5 - CAENORHABDITIS ELEGANS.
GBB5_HUMAN GUANINE NUCLEOTIDE-BINDING PROTEIN BETA SUBUNIT 5 (TRANSDUCIN BETA CHAIN 5) - HOMO SAPIENS (HUMAN).
GBB5_MOUSE GUANINE NUCLEOTIDE-BINDING PROTEIN BETA SUBUNIT 5 (TRANSDUCIN BETA CHAIN 5) - MUS MUSCULUS (MOUSE), AND RATTUS NORVEGICUS (RAT).
GBB_ARATH GUANINE NUCLEOTIDE-BINDING PROTEIN BETA SUBUNIT - ARABIDOPSIS THALIANA (MOUSE-EAR CRESS).
GBB_CRYPA GUANINE NUCLEOTIDE-BINDING PROTEIN BETA SUBUNIT - CRYPHONECTRIA PARASITICA (CHESNUT BLIGHT FUNGUS) (ENDOTHIA PARASITICA).
GBB_DICDI GUANINE NUCLEOTIDE-BINDING PROTEIN BETA SUBUNIT - DICTYOSTELIUM DISCOIDEUM (SLIME MOLD).
GBB_LOLFO GUANINE NUCLEOTIDE-BINDING PROTEIN BETA SUBUNIT - LOLIGO FORBESI (NORTHERN EUROPEAN SQUID).
GBB_LYMST GUANINE NUCLEOTIDE-BINDING PROTEIN BETA SUBUNIT - LYMNAEA STAGNALIS (GREAT POND SNAIL).
GBB_MAIZE GUANINE NUCLEOTIDE-BINDING PROTEIN BETA SUBUNIT - ZEA MAYS (MAIZE).
GBB_NICPL GUANINE NUCLEOTIDE-BINDING PROTEIN BETA SUBUNIT - NICOTIANA PLUMBAGINIFOLIA (LEADWORT-LEAVED TOBACCO).
GBB_ORYSA GUANINE NUCLEOTIDE-BINDING PROTEIN BETA SUBUNIT - ORYZA SATIVA (RICE).
GBB_SCHPO GUANINE NUCLEOTIDE-BINDING PROTEIN BETA SUBUNIT - SCHIZOSACCHAROMYCES POMBE (FISSION YEAST).
GBB_SOLTU GUANINE NUCLEOTIDE-BINDING PROTEIN BETA SUBUNIT - SOLANUM TUBEROSUM (POTATO).
GBB_YEAST GUANINE NUCLEOTIDE-BINDING PROTEIN BETA SUBUNIT - SACCHAROMYCES CEREVISIAE (BAKER'S YEAST).
O64944 G PROTEIN BETA SUBUNIT - AVENA FATUA.
O74214 G-PROTEIN BETA SUBUNIT - EMERICELLA NIDULANS (ASPERGILLUS NIDULANS).
O74855 TRP-ASP REPEAT CONTAINING PROTEIN - SCHIZOSACCHAROMYCES POMBE (FISSION YEAST).
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