The Complete Amino‐Acid Sequence of Histone H2B₍₁₎ from Sperm of the Sea Urchin Parechinus angulosus

Two histones have been isolated and purified from sperm cells of the sea urchin Parechinus angulosus . They have been designated sperm histone H2B (1) Parechinus and sperm histone H2B (2) Parechinus on criteria of solubility and partial sequence homology with H2B calf . H2B (1) consists of a polypeptide chain of the following 144 amino acid residues: Pro‐Ser‐Gln‐Lys‐Ser‐Pro‐Thr‐Lys‐Arg‐Ser‐Pro‐Thr‐Lys‐Arg‐Ser‐Pro‐Thr‐Lys‐Arg‐Ser‐Pro‐Gln‐Lys‐Gly‐Gly‐Lys‐Gly‐Gly‐Lys‐Gly‐Ala‐Lys‐Arg‐Gly‐Gly‐Lys‐Ala‐Gly‐Lys‐Arg‐Arg‐Arg‐Gly‐Val‐Gln‐Val‐Lys‐Arg‐Arg‐Arg‐Arg‐Arg‐Arg‐Glu‐Ser‐Tyr‐Gly‐Ile‐Tyr‐Ile‐Tyr‐Lys‐Val‐Leu‐Lys‐Gln‐Val‐His‐Pro‐Asp‐Thr‐Gly‐Ile‐Ser‐Ser‐Arg‐Ala‐Met‐Ser‐Val‐Met‐Asn‐Ser‐Phe‐Val‐Asn‐Asp‐Val‐Phe‐Glu‐Arg‐Ile‐Ala‐Ala‐Glu‐Ala‐Gly‐Arg‐Leu‐Thr‐Thr‐Tyr‐Asn‐Arg‐Arg‐Ser‐Thr‐Val‐Ser‐Ser‐Arg‐Glu‐Val‐Gln‐Thr‐Ala‐Val‐Arg‐Leu‐Leu‐Leu‐Pro‐Gly‐Glu‐Leu‐Ala‐Lys‐His‐Ala‐Val‐Ser‐Glu‐Gly‐Thr‐Lys‐Ala‐Val‐Thr‐Lys‐Tyr‐Thr‐Thr‐Ser‐Arg. In a previously published partial sequence serine was incorrectly assigned to position 30. A comparison of the carboxyl‐terminal two thirds of H2B (1) Parechinus and H2B calf reveals that 79% of the corresponding positions are occupied by identical amino acid residues. Much of the variability occurs in a short polar region of 20 amino acid residues. The remainder of C‐terminal regions is hydrophobic and almost completely invariable. A comparison of the amino‐terminal one third of H2B (1) Parechinus and H2B calf reveals that they are both highly basic with a considerable homology of the position of basic amino acids. Further, H2B (1) Parechinus possesses an amino terminal extension of 19 amino acids. These 19 amino acids can be recognized as a repeating pentapeptide.