Final answer:
The reading frame for a protein starts with the start codon (AUG) and continues until a stop codon is encountered. Without more context, the reading frame for GST-DHFR-His cannot be exactly determined from the provided sequence. Nonsense mutations can affect reading frames by introducing premature stop codons.
Step-by-step explanation:
When referring to the reading frame for the GST-DHFR-His protein, it is essential to understand that in molecular biology, an open reading frame (ORF) is a part of a reading frame that has the potential to code for a protein. It starts with a start codon (AUG), which codes for the amino acid methionine, and continues with subsequent codons until a stop codon (UAG, UGA, UAA) is reached. The provided sequence AUGACGGAU AGCCGCA AUAGGAAUUGGCGUUUAAG GCG suggests the presence of a start codon at the beginning, but without additional context or a longer nucleotide sequence, determining the exact reading frame for the protein is not possible.
It is also important to note that variations in the nucleotide sequence, such as a nonsense mutation, may impact the reading frame and protein synthesis. Such mutations introduce a premature stop codon and halt translation, producing an incomplete and often nonfunctional protein. Furthermore, there might be regulatory elements or domains, such as the HIGH-motif or KMSKS-motif, involved in protein function.