High impact information on GNP1

• Direct immunofluorescence showed large increases in the expression of Gnp1 and Bap2 proteins when grown in galactose compared with glucose medium [1].
• In contrast to Agp1p, Gnp1p is not functionally expressed when cells are grown on media containing proline as sole nitrogen source [2].
• Helix III was affected in both CAN1 (Y173H, Y173D) and GNP1 (W239C) mutants and has previously been found to be important for substrate preference in other members of the family [3].
• Constitutive overexpression of the genes for glutamine permease ( GNP1) or methionine permease ( MUP1) enhanced the assimilation of glutamine or methionine in the ssy1Delta strain but could not fully suppress the derepression of the NCR-sensitive genes or MET genes [4].
• While Gap1p and Agp1p appear to be the main cysteine transporters on the non-repressing nitrogen source proline, Bap2p, Bap3p, Tat1p, Tat2p, Agp1p and Gnp1p are all important for cysteine uptake on ammonium-based medium [5].

Biological context of GNP1

• The amino-acid sequence of GNP1, and its hydropathy profile of 12 transmembrane domains, closely resemble those of known amino-acid permeases [6].
• Amino acid residues important for substrate specificity of the amino acid permeases Can1p and Gnp1p in Saccharomyces cerevisiae [3].

Associations of GNP1 with chemical compounds

• The Km of GNP1 for glutamine uptake was determined to be 0.59 mM [6].
• Gnp1p, which is closely related to Agp1p, has a somewhat less-broad specificity, transporting Leu, Ser, Thr, Cys, Met, Gln and Asn, while Bap2p and Bap3p, which are also closely related to Agp1p, are able to transport Ile, Leu, Val, Cys, Met, Phe, Tyr and Trp [7].

Other interactions of GNP1

• Furthermore, whereas Bap2p, Bap3p, Tat1p and Tat2p seem most important under amino acid-rich conditions, Agp1p contributes significantly when only ammonium is present, and Gnp1p only contributes under the latter condition [5].

References