The primary structure of non-histone chromosomal protein HMG17 from chicken erythrocyte nuclei.

Chromatin contains a group of non-histone proteins called the high mobility group (HMG) proteins (reviewed [l]). There are 4 main HMG proteins in calf thymus, HMG 1,2, 14 and 17, which have all been shown to be present in isolated nucleosomes [2]. Some minor HMG protein components of calf thymus chromatin have also been characterised [3]. Attention has been focused on HMG14 and 17 because of their possible role in gene transcription [4,5]. The complete amino acid sequences of calf thymus HMG14 and 17 have been determined [6,7] and partial sequences are available for HMG1 and 2 [ 1,8]. HMG proteins have been shown to be present in a variety of organisms and tissues, including avian erythrocytes [9,10] trout testis and liver [11,12] and wheat and yeast [ 131 but little is known about the structures of the HMG proteins from these sources. One of the questions that needs to be answered concerning the HMG proteins is whether they exhibit the same extreme evolutionary stability as shown by the nucleosome core histones. As part of a programme of study on the structure of HMG proteins from various species we have now determined the complete amino acid sequence of HMG17 from chicken erythrocyte nuclei.