There are several ways you can try to predict the function of a sequence. A
much-used method is to search for homologs with a known function, either in other species (orthologs), or in the same
species (paralogs). Do you think Blast is a good tool for this? What kind of hits would you look for when
searching for homologs? Think about significance (E-value: the probability of matching a random sequence in
the database by chance) and annotation (description, references).
blastx searches protein database using a translated nucleotide query (in all possible 6 reading frames). In other words, blastx gives you the
closest protein sequence your nucleotide sequence will translate into (obviously
if it is in the database).