Enables pyruvate dehydrogenase (NAD+) activity. Acts upstream of or within mitochondrial acetyl-CoA biosynthetic process from pyruvate. Located in mitochondrion. Is expressed in several structures, including alimentary system; metanephros; nervous system; respiratory system; and sensory organ. Human ortholog(s) of this gene implicated in pyruvate decarboxylase deficiency. Orthologous to human PDHA1 (pyruvate dehydrogenase E1 subunit alpha 1). [provided by Alliance of Genome Resources, Apr 2022]