ABSTRACT
The discovery and subsequent initial characterization of the group of chromosomal proteins called the high mobility group (HMG) proteins has created considerable interest because of the suggestion that they may be associated with active genes. The groundwork of good protein chemistry in terms of fractionation, isolation, characterization, and structure laid the foundation for the subsequent functional work. The trout protein H6 has considerable sequence homologies with calf HMG17, including a proline-rich region, but being smaller H6 has a number of deletions. Two of these proteins, HMG19A and 19B, resemble HMG14 and 17 in their amino acid compositions and a third, HMG18, resembles histones H1 and H5, but further characterization of these proteins is required before we can classify them with confidence in the low molecular weight HMG group. Most of the amino acid sequence of calf HMG1 has been published together with that of the unfractionated HMG2.
