Genetic studies of human apolipoproteins. II. A rapid one‐dimensional isoelectric focusing technique to characterize apolipoproteins A‐I, A‐II, A‐IV and C‐II of unfractionated plasma

A simple and rapid one‐dimensional analytical isoelectric focusing method followed by immunoblotting is described which detects genetic and biochemical variation in apolipoproteins A‐I, A‐II, A‐IV and C‐II without prior ultracentrifugation and delipidation of plasma samples. A polipoproteins separated on an isoelectric focusing gel are sequentially transferred to two nitrocellulose membranes and pairs of apolipoproteins are identified on each membrane by immunological reactions. The specificity of the primary antibody and the sensitivity gained by use of a second, alkaline phosphatase conjugated anti‐IgG allows the detection of free apolipoproteins in serum or plasma. A pH gradient 4–6.5 is suitable to identify the four apoproteins tested from a single gel and there is little loss of isoprotein resolution in sequential blots. Only 2 μL of whole plasma is required and results on 50 samples can be obtained from a single horizontal gel within one day.