How to determine which is the nucleotide sequence of a gene? I have came across a few genes that show different nucleotide sequence in different databases. I then found out that the sequences are actually reverse complement of each other. How do i determine which is the actual nucleotide sequence of a gene,and not the reverse complement version of it?

You run a blast of your sequence. Then explore the results and you'll see somewhere that says "strand" and is indication whether is plus/minus.

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Also blast has a graphical interface in which you'll clearly see the matching and non-matching bases. Therefore it should help you to identify the differences between the 2 sequences.