High impact information on BAP2

• Direct immunofluorescence showed large increases in the expression of Gnp1 and Bap2 proteins when grown in galactose compared with glucose medium [1].
• The BAP3 gene of Saccharomyces cerevisiae encodes a protein with a high similarity to the BAP2 gene product, a high-affinity permease for branched-chain amino acids [2].
• It was determined that PTR3 also modulates expression of BAP2, the gene encoding the branched-amino acid permease [3].
• The transcription of Lg-BAP2 was not induced by the addition of leucine to the growth medium, while that of cer-BAP2 was induced [4].
• The transcription of Lg-BAP2 was repressed by the presence of ethanol and weak organic acid, while that of cer-BAP2 was not affected by these compounds [4].

Biological context of BAP2

• The BAP2 promoter contains one or two putative Gcn4p binding sites and one putative Leu3p binding site [5].
• We present evidence that the zinc-finger proteins Stp1p and Stp2p bind directly to the BAP2 promoter [6].
• Although the transcriptional controls of BAP2 have been well studied, the posttranslational down-regulation mechanisms for Bap2p have not been established [7].
• We isolated the gene BAP2 as a multicopy suppressor of the YPD- phenotype of aat1leu2 yeast [8].
• In order to align the genetic and biochemical studies of leucine uptake we completed a detailed kinetic analysis of yeast strains in which the BAP2 gene was disrupted and compared this to the kinetics of uptake of the parental strain [8].

Anatomical context of BAP2

• This elevation is interpreted to be partly the result of an increased level of the Bap2p permease in the plasma membrane, because deletion of BAP2 slightly decreases the induction of uptake [5].

Associations of BAP2 with chemical compounds

• Induction of BAP2 transcription by leucine is accompanied by an increase in branched-chain amino acid uptake [5].
• Addition of (L)-leucine to minimal proline medium, on the other hand, has no effect on BAP2 transcription [5].
• The capacity of Leu3p to activate BAP2 transcription correlates with conditions that affect the level of alpha-isopropyl malate [6].

Physical interactions of BAP2

• The presence of a Leu3p binding site in the BAP2 promoter is required for full promoter activity on synthetic complete medium [6].

Enzymatic interactions of BAP2

• The N-terminal domain of yeast Bap2 permease is phosphorylated dependently on the Npr1 kinase in response to starvation [9].

Regulatory relationships of BAP2

• As a simple hypothesis we propose that Stp1p is a transcription factor which activates BAP2, and probably other amino-acid permease genes [10].

Other interactions of BAP2

• Mutations in PTR3, BAP2 and SSY1 disrupt sensing and transport of extracellular leucine [11].
• There is still a leucine-inducible increase in branched-chain amino acid uptake in a delta gap1 delta bap2 strain, indicating that BAP2 shares leucine induction with at least one remaining branched-chain amino acid-transporting permease [5].
• The transcriptional activity of the BAP2 promoter is affected by a number of genes, including SSY1, which encodes an amino acid permease homologue that is necessary for transcription of BAP2 [6].
• STP1, a gene involved in pre-tRNA processing in yeast, is important for amino-acid uptake and transcription of the permease gene BAP2 [10].
• The effect of a tup1 deletion on BAP2 transcription depends on SSY1 [6].

References