Preparations of Homeostatic Thymus Hormone Consist Predominantly of Histones 2A and 2B and Suggest Additional Histone Functions

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 82; no. 15; pp. 4871 - 4875
• Main Authors: Reichhart, Robert, Zeppezauer, Michael, Jornvall, Hans
• Format: Journal Article
• Language: English
• Published: Washington, DC National Academy of Sciences of the United States of America 01.08.1985; National Acad Sciences
• Subjects: Amino Acid Sequence; Amino acids; Animals; Binding Sites; Biochemistry; Biological and medical sciences; Cattle; Cell physiology; Electrophoresis; Fundamental and applied biological sciences. Psychology; Gels; Histones; Histones - isolation & purification; Histones - physiology; Hormonal regulation; Hormones; Macromolecular Substances; Molecular and cellular biology; Protein Precursors - metabolism; Protein Processing, Post-Translational; Regional identity; Thymopoietins; Thymus hormones; Thymus Hormones - analysis; Ubiquitins; Protein hormone; Histone H2B; Purification; Histone H2A; Animal; Calf; Homeostasis; Primary structure; Chemical composition; Thymus hormone; Structure function relationship; Nuclear protein
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.82.15.4871

The two major constituents in preparations of the homeostatic thymus hormone (HTH) were purified. Amino acid sequence analysis showed that the components (HTHαand HTHβ) are identical to histones H2A and H2B, suggesting the possibility that histones might have hitherto unrecognized occurrence and functions. If the HTH activities are not ascribed to the two histones in the preparation, they could only be derived from minor constituents present in minimal amounts. Therefore, the histone structures were scrutinized for properties of relevance in relation to hormone activities and for similarities with thymic hormones. Similarities between COOH-terminal regions of histones H2A, H2B, and H3 were noticed, as well as some similarities between NH2-terminal regions of histones and parts of recognized thymus hormones and related proteins. Potential signals, resembling cleavage sites in prohormones, are present in the histone structures, and further correlations with recently discovered ubiquitin functions may explain molecular mechanisms for actions of the HTH preparations. None of the observations is significant by itself, but the combined results suggest the hypothesis of different relationships and functions, including hormone-like activities, for some histones.