Final answer:
The pre-mRNA processing step that is important for initiating translation is 5' capping.
Step-by-step explanation:
The pre-mRNA processing step that is important for initiating translation is 5' capping. While the pre-mRNA is still being synthesized, a 7-methylguanosine cap is added to the 5' end of the growing transcript. This cap protects the mRNA from degradation and helps initiate translation by ribosomes.