Structural analysis of the glycine-rich, arginine-rich histone. 3. Sequence of the amino-terminal half of the molecule containing the modified lysine residues and the total sequence.

1. The amino acid sequence of the amino-terminal portion of the glycine-rich, arginine-rich histone (Residues 1 to 49) has been determined from studies on the tryptic, chymotryptic, and thermolysin peptides. This sequence overlaps with that of the carboxylterminal portion (Residues 50 to 102) defined previously to give the following sequence: acetylserGly-Arg-Gly-Lys-Gly-Gly-Lys-Gly-Leu-Gly-Lys-GlyGly-Ala-Lys(Ac)-Arg-His-Arg-Lys(Me)-Val-Leu-ArgAsp-Asn-Ile-Gln-Gly-Ile-Thr-Lys-Pro-Ala-Ile-Arg-ArgLeu-Ala-Arg-Arg-Gly-Gly-Val-Lys-Arg-Ile-Ser-Gly-LeuIle-Tyr-Glu-Glu-Thr-Arg-Gly-Val-Leu-Lys-Val-PheLeu-Glu-Asn-Val-Ile-Arg-Asp-Ala-Val-Thr-Tyr-ThrGlu-His-Ala-Lys-Arg-Lys-Thr-Val-Thr-Ala-Met-AspVal-Val-Tyr-Ala-Leu-Lys-Arg-Gln-Gly-Arg-Thr-LeuTyr-Gly-Phe-Gly-Gly-COOH. 2. This sequence agrees with that reported recently by DeLange, Fambrough, Smith, and Bonner (J. Biol. Chem., 244, 319 (1969)) except that the arginine residue they placed at position 44 is found in position 40 (and is italicized) in the above sequence. 3. Four clusters of basic residues (underlined) were present in this sequence. The cluster in the amino-terminal portion contained both the modified amino acids t-Nacetyllysine and t-N-methyllysine at positions 16 and 20. The acetyllysine was present in approximately half of the glycine-rich, arginine-rich histone molecules; the methylated lysine position contained mono and dimethyl groups in a ratio of 1:3. This microheterogeneity makes a total of four possible species of the glycine-rich, arginine-rich histone.