Ambiguity of gene action

Abstract

Realization of information from gene (DNA) up to the specific enzyme activity is being considered The process consists of the following general steps: transcription, translation, polypeptide chain folding and in particular cases assembly of protein subunits. Genetic control of the steps is evident now. It makes possible to consider consequences of mutational alterations for different stages of gene realization. Furthermore it is possible to apply methods of genetic analysis for studying the very gene action. One of the promising genetical approaches to the problem is the study of suppression on the level of translation (and possibly transcription). Consideration of suppression mechanisms known so far points on the possibility of ambiguity in translation of genetic message. Experimental data presented in the paper and in several other publications show the existence of suppressors, namely weak suppressors (known as modifier genes) in strains of microorganisms used in experimental work. So the situation conforms possibility of ambiguous translation within the living cell. Besides that a few available direct evidences of translational ambiguity in vivo are presented. It is necessary to distinguish between the ambiguity of translation and ambiguity of gene action in general. So the latter one means hot only the possibility of translational mistakes but simultaneously a considerable stability of the phenotype. Nonexpressivity of some amino acid substitution in proteins is one of the possible mechanisms for maintaining the phenotypic stability. Another mechanism of this type is "correction" of some mutational defects in proteins on the level of the multimeric structure. On the other hand these mechanisms can considerably amplify the ambiguity in relation between gene and phenotypic character. The possible role of the ambiguity of gene action in living things is being discussed.