Multifunctional Proteins
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CULAR BIOPHYSICS
Multifunctional Proteins A. B. Uzdensky* Laboratory of Molecular Neurobiology, Academy of Biology and Biotechnology, Southern Federal University, Rostov-on-Don, 344090 Russia *e-mail: [email protected] Received November 30, 2019; revised November 30, 2019; accepted February 3, 2020
Abstract—A surprisingly small number of human genes (19–20 thousand) is not consistent with a much larger number of proteins and the number of their functions. One of the factors of functional diversity is the multifunctionality of proteins. An important subclass of such proteins is moonlighting proteins, in which one polypeptide chain performs two or more functions under different conditions. Often, these are various housekeeping proteins – glycolytic, ribosomal, and others, which are abundant in the cell. In this review we consider the structures and functions of several such proteins – the rpS3 ribosomal protein, cytochrome c, glyceraldehyde-6-phosphate dehydrogenase (GAPDH), transcription factors STAT3, β-catenin and p53. A switching of their functions occurs due to violation of the balance between their synthesis, use, and degradation, intracellular relocalization, and post-translational modifications. A significant role of the internal disordered regions in the formation of intermolecular complexes with other proteins and nucleic acids is noted. The emergence of multifunctional proteins during evolution is discussed. Keywords: multifunctional proteins, cytochrome c, GAPDH, β-catenin, STAT3, p53 DOI: 10.1134/S0006350920030227
INTRODUCTION Molecular biology of the twentieth century was based on the classical postulates, such as “DNA contains the information on the structure of all proteins and RNA in the organism.” Data on all proteins and RNA of the body is found in DNA. One more postulate was formulated by Beadle and Tatum (1941): “One gene – one enzyme” [1], which was later transformed into: “One gene—one protein,” and after refinement— “One cistron—one polypeptide chain.” Another important postulate was formulated by Anfinsen [2]: “The primary protein structure, i.e. the amino acid sequence, which is unambiguously determined by the nucleotide sequence in DNA, unambiguously determines its spatial structure and functional activity.” However, the last data showed that these statements are not accurately consistent with the current state of molecular biology. It was early assumed the existence of about a million genes in a human genome. Then their number was reduced to 40–100 thousand. Abbreviations: P—platform; PTM—posttranslational modification; E—enzyme; Apaf-1—Apoptotic protease-activating factor 1; CTD—C-terminal domain; DBD—DNA-binding domain; GAPDH—glyceraldehyde-6-phosphate dehydrogenase; IDR—intrinsically disordered region; MLP—moonlighting proteins; NLS—nuclear localization sequence; p53RE— p53-response element; SLiM—short linear motif; SNP—single nucleotide polymorphism; STAT3—signal transducer and activator of transcription 3; TAD—transactivation domain; TET— tetramerization domain.
But in the early 21st c
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