Fetal and Newborn Calf Thymus as a Source of Chromatin Proteins: Purification of HMG-1 and HMG-2

Abstract
The high mobility group (HMG) non-histone chromosomal proteins were first isolated from calf thymus' but were later found in numerous organs of many vertebrates.' The proteins can be extracted from calf thymus 1 with 0.35 M NaCl and they are quite soluble in 2% trichloroacetic acid. We have shown that members of the HMG-1 family (i.e., HMG-1, HMG-2, and HMG-E) exhibit a preferential affinity for single-stranded DNA at roughly physiological ionic trength. Members of this family have other intriguing properties (see references 6 and 7 for recent reviews), including the ability to assemble nucleosomes in vitroe8 The architecture of the proteins strongly suggests that they are designed to interact simultaneously with histones and with DNA through physically distinct domains6, 9.