On the development of a standard two-dimensional polypeptide map of the human X chromosome.

Two-dimensional gel electrophoresis analysis of a rodent-human somatic cell hybrid containing the X as the only human chromosome reveals three polypeptides that are absent in the parental cell line. The presence of these spots in human female fibroblasts indicates their human origin. The polypeptides have molecular weights and isoelectric points of 30,000/5.8,37,000/5.4, and 57,000/4.7 and are designated as PFHG 1, PFHG 2, and PFHG 3. Comparison of their molecular characteristics with those of polypeptides assigned to the human X in two other investigations shows that some but not all polypeptides are similar. Factors are discussed that might interfere with the rapid development of a standardized polypeptide map of the human X.