The heterotetramer with HSD17B8 has NADH-dependent 3-ketoacyl-acyl carrier protein reductase activity, and thereby plays a role in mitochondrial fatty acid biosynthesis. Within the heterotetramer, HSD17B8 binds NADH; CBR4 binds NADPD. The homotetramer has NADPH-dependent quinone reductase activity. Both homotetramer and the heterotetramer have broad in vitro substrate specificity and can reduce 9,10-phenanthrenequinone, 1,4-benzoquinone and various other o-quinones and p-quinones. Lipid metabolism; fatty acid biosynthesis. Homotetramer (in vitro). Heterotetramer with HSD17B8; contains two molecules each of HSD17B8 and CBR4. Belongs to the short-chain dehydrogenases/reductases (SDR) family.