The amino acid composition of a protein influences its expression

Abstract

The quantity of each protein in a cell only is only partially correlated with its gene transcription rate. Independent influences on protein synthesis levels include mRNA sequence motifs, amino acyl-tRNA synthesis levels, elongation factor action, and protein susceptibility to degradation. Here we report two novel forms of interaction between the amino acid composition of a protein and its expression level. In animals, the differing origins of amino acids define a nutritional classification system and indicate their potential for scarcity – essential amino acids (EAA) are solely obtained from dietary supply, non-essential amino acids (NEAA) from biosynthetic supply, and conditionally essential amino acids (CEAA) from both. Accessing public proteomic datasets, we demonstrate that CEAA sequence composition is inversely correlated with expression – a rule of supply that is further magnified by rapid cellular proliferation. Similarly, proteins with the most extreme compositions of EAA are reduced in abundance.