A protein complex that catalyzes the reaction 3-methyl-2-oxobutanoate + lipoamide = S-(2-methylpropanoyl)-dihydrolipoamide + carbon dioxide (CO2). This requires thiamine diphosphate; the enzyme also acts on (S)-3-methyl-2-oxopentanoate and 4-methyl-2-oxo-pentanoate.
Source:PMID:15612914