/*
From NCBI feature table document :
http://www.ncbi.nlm.nih.gov/collab/FT/

Feature Key           attenuator
*Feature Key           C_region
*Feature Key           CAAT_signal
*Feature Key           CDS
Feature Key           D-loop
Feature Key           D_segment
Feature Key           enhancer
*Feature Key           exon
Feature Key           gap
*Feature Key           GC_signal
*Feature Key           gene
Feature Key           iDNA
*Feature Key           intron
Feature Key           J_segment
Feature Key           LTR
*Feature Key           mat_peptide
Feature Key           misc_binding
Feature Key           misc_difference
Feature Key           misc_feature
Feature Key           misc_recomb
*Feature Key           misc_RNA
*Feature Key           misc_signal
Feature Key           misc_structure
Feature Key           mobile_element
Feature Key           modified_base
*Feature Key           mRNA
*Feature Key           ncRNA
*Feature Key           N_region
Feature Key           old_sequence
Feature Key           operon
Feature Key           oriT
Feature Key           polyA_signal
Feature Key           polyA_site
*Feature Key           precursor_RNA
Feature Key           prim_transcript
Feature Key           primer_bind
*Feature Key           promoter
Feature Key           protein_bind
Feature Key           RBS
*Feature Key           repeat_region
Feature Key           rep_origin
*Feature Key           rRNA
*Feature Key           S_region
*Feature Key           sig_peptide
*Feature Key           source
Feature Key           stem_loop
*Feature Key           STS
*Feature Key           TATA_signal
Feature Key           terminator
*Feature Key           tmRNA
*Feature Key           transit_peptide
*Feature Key           tRNA
Feature Key           unsure
*Feature Key           V_region
*Feature Key           V_segment
*Feature Key           variation
Feature Key           3'UTR
Feature Key           5'UTR
*Feature Key           -10_signal
*Feature Key           -35_signal



----------------------------------
From Swissprot :
http://web.expasy.org/docs/userman.html#FT_keys
INIT_MET
SIGNAL
PROPEP
TRANSIT
CHAIN
PEPTIDE
TOPO_DOM
TRANSMEM
INTRAMEM
DOMAIN
REPEAT
CA_BIND
ZN_FING
DNA_BIND
NP_BIND
REGION
COILED
MOTIF
COMPBIAS
*ACT_SITE
METAL
BINDING
SITE
NON_STD
MOD_RES
LIPID
*CARBOHYD
DISULFID
CROSSLNK
VAR_SEQ
*VARIANT
MUTAGEN
UNSURE
CONFLICT
NON_TER
NON_CONS
*HELIX
*STRAND
*TURN


