AST1 is a cytoplasmic protein associated with the periplasmic membrane in yeast
This group contains members identified in targeting of yeast membrane proteins ATPase. AST1 is a cytoplasmic protein associated with the periplasmic membrane in yeast, identified as a multicopy suppressor of pma1 mutants which cause temperature sensitive growth arrest due to the inability of ATPase to target to the cell surface. This family is homologous to the medium chain family of dehydrogenases and reductases. Medium chain dehydrogenases/reductase (MDR)/zinc-dependent alcohol dehydrogenase-like family, which contains the zinc-dependent alcohol dehydrogenase (ADH-Zn) and related proteins, is a diverse group of proteins related to the first identified member, class I mammalian ADH. MDRs display a broad range of activities and are distinguished from the smaller short chain dehydrogenases (~ 250 amino acids vs. the ~ 350 amino acids of the MDR). The MDR proteins have 2 domains: a C-terminal NAD(P) binding-Rossmann fold domain of an beta-alpha form and an N-terminal catalytic domain with distant homology to GroES.