Yeast adenylate kinase is transcribed constitutively from a promoter in the short intergenic region to the histone H2A-1 gene

Yeast mitochondrial adenylate kinase (high molecular mass form, gene locus: AKY2) is encoded on chromosome IV of the same DNA strand as histone H2A-1. The nontranslated intergenic region spans 560 bp, the nontranscribed spacer can be estimated to comprise at most 300 bp. The TATA-box sequence is contained in a striking environment consisting of 20 alternating pyrimidines and purines. The AKY2 transcript is made constitutively: (i) the cellular mRNA concentration does not vary significantly with either growth conditions or elapse of the cell cycle; (ii) β-galactosidase activity is about constant in yeast cells grown on various carbon sources after transformation with AKY2-promoter/lacZ fusions; (iii) primer elongation analysis shows that utilization of 5 initiation sites is qualitatively and quantitatively independent of the growth conditions and the carbon source used; (iv) Western blot analysis and adenylate kinase activity measurements indicate the absence of post-transciptional controls as well.