DAMN YOU GENES!

You hope to study a gene that codes for a neurotransmitter (NT) protein in human brain cells.  You know the amino acid sequence of the protein - how do you: A) identify the genes expressed in a specific type of brain cell, b)ID the gene for the NT, c)produce multiple copies of of the gene, and d) produce a quantity of the NT for evaluation as a potential medication.

any help?? im lost on this one...but if I had to take a guess... for a) look up sequence in worldwide database?  im lost on  the others...

Lets see...,
1)cut out a chunk of the brain.
2)Extract DNA + proteins
3)...
4)Profit!
Either that, or use some combination of restriction enzymes, PCR, Southern blotting, and hope that someone knows what they're doing.
PCR should at least let you make copies of it.
http://en.wikipedia.org/wiki/Polymerase_chain_reaction

a) You can search around the NCBI BLAST database.  There are a bunch of different search algorithms for nucletoides and proteins.  I don't know what all of them do though.

b) It would be hard because you have to deal with introns in the DNA, so you couldn't just go backwards from the amino acids to the DNA, (not that you could do that anyway, because of degeneracies in the code).  For a and b though, you would need some kind of searching algorithm, unless you happened to know what the sequence was in a related species, then you could do a southern blot with that DNA sequence as a probe.

c,d) You could use a restriction digest, southern blot with a labelled probe corresponding to the base sequence you wish to pull out, then gel purify and extract.  Design primers to PCR, then ligate into a competent vector for transfection into yeast.  Overproduce in yeast, and most likely you would have to reconstitute in lipid vesicles if this is some kind of channel protein in brain cells.

Oh, you could also do a Northern to isolate the mRNA, and then reverse transcriptase, although there is still degeneracy you have to deal with in the probe...