Search results for GNGT1

Showing 9 results out of 9

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Protein (3 results from a total of 3)

Identifier: R-HSA-167428
Species: Homo sapiens
Compartment: plasma membrane
Primary external reference: UniProt: GNGT1: P63211
Identifier: R-HSA-55393
Species: Homo sapiens
Compartment: photoreceptor disc membrane
Primary external reference: UniProt: GNGT1: P63211
Identifier: R-HSA-2530520
Species: Homo sapiens
Compartment: photoreceptor disc membrane
Primary external reference: UniProt: P63211

Reaction (4 results from a total of 4)

Identifier: R-HSA-2530501
Species: Homo sapiens
Compartment: photoreceptor disc membrane, cytosol
Prenylation is the process of post-translational addition of hydrophobic groups to proteins and is thought to help anchor proteins to cellular membranes. Farnesylation is a type of prenylation, where a farnesyl group (donated from farnesyl diphosphate, FPP) is added to a cysteine residue on a protein. The enzyme mediating this transfer is farnesyltransferase (FNT). FNT is a heterodimer comprising an alpha subunit (common to another prenylating enzyme called geranylgeranyltransferase, GGT) and a unique beta subunit (Long et al. 2001, Bell et al. 2002, deSolms et al. 2003). This complex recognises the CAAX box (C is the cysteine, A is any aliphatic amino acid, and X determines which enzyme acts on the protein) at the C-terminus of the target protein, in this case, the gamma subunit of transducin (GNG1) (Omer at al. 1993).
Identifier: R-HSA-74882
Species: Homo sapiens
Compartment: photoreceptor disc membrane
Once transducin alpha subunit (GNAT1) is deactivated by hydrolysis of bound GTP to GDP, it reassociates with transducin beta:gamma subunits (GNB1:GNGT1) to form inactive transducin (Gt-GDP). A stoichiometric overabundance of GNB1:GNGT1 facilitates the reassociation event. The details for this event were revealed in bovine experiments (Clark et al. 2006, Fung et al. 1981).
Identifier: R-HSA-2485182
Species: Homo sapiens
Compartment: photoreceptor disc membrane
Binding of transducin (Gt) to activated rhodopsin (MII) promotes the release of GDP from the Gt alpha subunit enabling a GTP (present in a higher concentration than GDP) to take its place. With GTP bound, Gt alpha (GNAT1-GTP) dissociates from the Gt beta:gamma subunits (GNB1:GNGT1) and from MII. MII is then available to bind and activate additional transducins. Transducin activation is the first amplifying step in visual transduction. Many findings came from bovine experiments (Pugh & Lamb 1993, Fung & Stryer 1980, Fung et al. 1981, Hofmann 1985).
Identifier: R-HSA-2485180
Species: Homo sapiens
Compartment: cytosol, photoreceptor disc membrane
In darkness, the G protein transducin (Gt) is attached to the disk membrane surface with a GDP bound to it and it is inactive. Gt is a heterotrimer of alpha1 (GNAT1) (van Dop et al. 1989, Fong 1992), beta1 (GNB1) (Codina et al. 1986) and gamma1 (GNGT1) (Tao et al. 1993) subunits. Photoactivated rhodopsin (MII or R*) catalyzes the exchange of GTP for GDP bound to Gt. Upon GTP/GDP exchange, Gt is released from MII and the Gt alpha with GTP bound (GNAT1 GTP) dissociates from Gt beta gamma subunits (GNB1:GNGT1). This mechanism was deciphered from bovine experiments (Pugh & Lamb 1993). MII proceeds to activate additional Gt molecules, making this reaction the first amplification step in the phototransduction cascade. A single activated rhodopsin molecule activates tens of Gt molecules. Although phosphorylation of activated rhodopsin (MII) by rhodopsin kinase (GRK1) reduces transducin activation (Khani et al. 1996), complete deactivation occurs only after arrestin (S-antigen or SAG, Yamaki et al. 1988) binds to and sterically caps MII.

Defects in GNAT1 cause the Nougaret type of autosomal dominant, congenital stationary night blindness (Dryja et al. 1996, CSNBAD3; MIM:610444) . Congenital stationary night blindness is a non progressive retinal disorder characterized by impaired night vision.

Complex (1 results from a total of 1)

Identifier: R-HSA-74061
Species: Homo sapiens
Compartment: photoreceptor disc membrane

Icon (1 results from a total of 1)

Species: Homo sapiens
Curator: Bruce May
Designer: Cristoffer Sevilla
GNGT1 icon
Guanine nucleotide-binding proteins (G proteins) are involved as a modulator or transducer in various transmembrane signaling systems
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