Frameshift mutations, protein synthesis

The small subunit 16S rRNA also contains regions that appear to be involved in translational accuracy. In particular, substitutions at nucleotides in the so-called 530 loop lead to changes in the error rate of protein synthesis. This rRNA loop is known to be spatially near the proteins S4, S5, and SI2, and effects of nucleotide changes in the 530 loop parallel those observed for the proteins. Thus, the rRNA and proteins in this part of the small subunit together act as a proofreading domain. Substitutions at some of these nucleotides increase the rate of missense or frameshift errors, while others are detrimental because they prevent binding of the EF-Tu GTP AA-tRNA ternary complex. Still other mutations actually increase the accuracy of translation, in that they make the ribosomes resistant to error-inducing antibiotics. 

HbA) have been reported. These molecules often differ from HbA by the insertion of an incorrect amino acid into either the a- or P-chains during protein synthesis. Other variants may be due to deletion or frameshift mutations (Section 17.7). Haemoglobin variants may function normally or abnormally depending on the nature and position of the substitution (Table 4.5). 

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