<p> Members of this family represent the alpha subunit of the mitochondrial multifunctional fatty acid degradation enzyme complex. Subunit activities include: enoyl-CoA hydratase (<db_xref db="EC" dbkey="4.2.1.17"/>) and 3-hydroxyacyl-CoA dehydrogenase (<db_xref db="EC" dbkey="1.1.1.35"/>). Some characterisation of these proteins has been done in human (<db_xref db="SWISSPROT" dbkey="P40939"/>), pig (<db_xref db="SWISSPROT" dbkey="Q29554"/>) and rat (<db_xref db="SWISSPROT" dbkey="Q64428"/>). The beta subunit has acetyl-CoA C-acyltransferase (<db_xref db="EC" dbkey="2.3.1.16"/>) activity.</p>