Final answer:
The correct answer is mRNA. SF1 remains at the exon-exon junction to form the exon junction complex (EJC) for export of the mature transcript to the cytoplasm.
Step-by-step explanation:
The correct answer is A) mRNA.
SF1 (splicing factor 1) remains at the exon-exon junction to form the exon junction complex (EJC) for export of the mature transcript to the cytoplasm. This EJC complex is involved in mRNA splicing and export. It helps in linking the exon sequences together after the removal of introns, ensuring the accurate and precise removal of introns and the rejoining of exons.
The exon junction complex (EJC) is a multiprotein complex that marks the position of exon-exon junctions following the process of splicing in pre-messenger RNA (pre-mRNA). SF1, or splicing factor 1, does not remain at the exon-exon junction to form the EJC. Instead, the EJC is involved in several post-splicing activities that are critical for mRNA processing. Among these, the EJC contributes to nuclear export of mRNA, ensures the fidelity of splicing, and participates in mRNA surveillance mechanisms like nonsense-mediated decay (NMD). The EJC is fundamentally associated with mRNA after completion of pre-mRNA splicing and not with tRNA, rRNA, or snRNA.