Immunogen sequence: RDEELVLPIN SSLSVTLHQD QLKTTTTAVI SKDFTEDRIW LNGREEDVGQ PRLQACLREI RCLARKRRNS RDGD. The enzyme mevalonate pyrophosphate decarboxylase catalyzes the conversion of mevalonate pyrophosphate into isopentenyl pyrophosphate in one of the ear