This group is predominated by atypical alcohol dehydrogenases; they exist as tetramers and exhibit specificity for NADP(H) as a cofactor in the interconversion of alcohols and aldehydes, or ketones. Like other zinc-dependent alcohol dehydrogenases (ADH) of the medium chain alcohol dehydrogenase/reductase family (MDR), tetrameric ADHs have a catalytic zinc that resides between the catalytic and NAD(H)binding domains; however, they do not have and a structural zinc in a lobe of the catalytic domain. The medium chain alcohol dehydrogenase family (MDR) has a NAD(P)(H)-binding domain in a Rossmann fold of a beta-alpha form. The N-terminal region typically has an all-beta catalytic domain. These proteins typically form dimers (typically higher plants, mammals) or tetramers (yeast, bacteria), and have 2 tightly bound zinc atoms per subunit.