On the presence of the chromosomal proteins HMG I and HMG Y in rat organs.

Using antiserum raised against HMG I, we have shown that HMG I and HMG Y are present in perchloric acid extracts of kidney, lung, heart, brain, liver and intestine in the rat, suggesting that the expression of these proteins may not be dependent upon proliferative activity. The results also show that the ratio between HMG I and HMG Y varies between different organs.

The amino acid sequence of the chromosomal protein HMG-Y, its relation to HMG-I and possible domains for the preferential binding of the proteins to stretches of A-T base pairs.

The primary structure of the human high mobility group (HMG) protein HMG-Y has been established except for a few amino acids in the N-terminal and the C-terminal part of the protein. It was found that the sequence was identical to that of HMG-I except for a run of eleven amino acids. Like HMG-I the protein was N-terminally blocked and the palindromic sequence Pro-Arg-Gly-Arg-Pro occurred twice as in HMG-I. The binding of peptides derived from HMG-I (after thermolysin cleavage) to poly (dA-dT).poly(dA-dT) suggested that there are at least two different binding domains in the protein and that binding is not dependent upon an intact protein.