METHYLCROTONYL-COA CARBOXYLASE BETA CHAIN, MITOCHONDRIAL PRECURSOR (EC 6.4.1.4) (3-METHYLCROTONYL-COA CARBOXYLASE 2) (MCCASE BETA SUBUNIT) (3-METHYLCROTONYL-COA:CARBON DIOXIDE LIGASE BETA SUBUNIT). [Source:SWISSPROT;Acc:Q9HCC0]