2-DIMENSIONAL ELECTROPHORESIS OF PLASMA-LIPOPROTEINS - RECOGNITION OFNEW APO-A-I-CONTAINING SUBPOPULATIONS

Two-dimensional electrophoresis has been used to resolve 12 distinct a po A-I-containing high-density lipoprotein (HDL) subpopulations in hum an plasma. The subpopulations were quantitated by I-125-labeled, monos pecific antibody and phosphor-imaging. Modification and standardizatio n of the agarose electrophoresis (first dimension) enabled us to,recog nize new HDL subpopulations. Lipoprotein mobilities in agarose were ex pressed relative to the mobility of the sample's endogenous albumin. W e demonstrated the presence of lipoproteins with mobilities faster tha n and similar to albumin, as well as subpopulations with mobilities sl ower than albumin. We refer to these as prealpha, alpha and prebeta, r espectively. Lipoprotein molecular sizes were determined with a non-de naturing polyacrylamide gradient gel electrophoresis (PAGE) (2% to 36% ) in the second dimension. Internal standard of I-125-labeled proteins of known molecular size was run simultaneously in each gel permitting accurate size determination. We have demonstrated that ultracentrifug ally-isolated lipoproteins are different from the native apo A-I-conta ining subpopulations. The major difference observed was the loss of pr ebeta1 and prebeta2 particles from the d < 1.21 g/ml fractions to the d > 1.21 g/ml fractions. Possible physiologic and pathologic implicati ons of these findings are also discussed.