RESOLUTION OF FIBRONECTIN AND OTHER UNCHARACTERIZED PROTEINS BY 2-DIMENSIONAL POLYACRYLAMIDE ELECTROPHORESIS WITH THIOUREA

Several proteins, which are recognized components of serum, are not re solved by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) under standard conditions, One major example is fibronectin, which is detected in fairly high concentration (milligram range) by immunoassa ys, while undetectable in 2D-PAGE gels. Following several experiments with a combination of zwitterionic and chaotropic substances we obtain ed a good resolution of the protein in gels containing 0.5 M thiourea plus 8 M urea. By this technique, fibronectin was, for the first time, found to be microheterogeneous between pI values of 5.3 and 5.6. Besi des fibronectin we detected three other families of uncharacterized pr oteins with M-r of 130 000, 110 000 and 34 000 respectively, whose ide ntity and function are currently under investigation. (C) 1998 Elsevie r Science B.V.