Immunochemical and Genetic Analyses of Isozymes

Recently we have demonstrated that human phosphofructokinase (PFK; ATP: D-fructose-6-P. 1 -phosphotransferase; EC.2.7.1 .1 1 ) is under the control of three structural loci that code for M (muscle-type), I (liver-type), and P (platelet-type) subunits; random tetramerization of these subunits produces various isozymes. In this study. we have produced and characterized BALB/c hybridoma antibodies to the Mand 1-type subunits of human PFK. The specific antibodies were detected by an enzyme-immunoprecipitation assay using Staphylococci-bearing protein A as an immunoadsorbent. Of the wells tested using red blood cell (RBC) PFK (M + 1). 61 % were positive. Only one Mspecific hybridoma was identified. The one anti-M and 4 anti-I antibodies were characterized for their biochemical and immunochemical specificities. To define the combining specificities of these antibodies, we compared their reactivity and that of monospecific rabbit anti-M antiserum with muscle and liver PFKs from 1 5 different vertebrate