Molecular basis for multiple forms of LDH‐X

Abstract The guinea pig has three molecular species of LDH‐X which are inhibited by antiserum directed against the C subunit. Only two of these are selectively inhibited by anti‐A polypeptide antiserum. Heterotetramers produced by in vitro dissociation and recombination of isozymes and containing B‐C subunit combinations are selectively inhibited only by the anti‐C antiserum. Therefore, the subunit composition of these multiple forms of LDH‐X are: CCCC; CCCA; CCAA. Similarly, rat testes contain two forms of LDH‐X which can be described as CCCC and CCCA tetramers.