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IMGT reference sequences in FASTA format:

Amino acid sequences without gaps

The FASTA header contains:
IMGT accession number | gene and allele name | species | functionality | exon name | domain name | domain type | alternative splicing (if it is) | partial (if it is) 
>AJ717664|BTLA*01|Homo sapiens|F|EX1|
MKTLPAMLGTGKLFWVFFLIPYLDIWNIH
>AJ717664|BTLA*01|Homo sapiens|F|EX2|[D]|C-LIKE|
GKESCDVQLYIKRQSEHSILAGDPFELECPVKYCANRPHVTWCKLNGTTCVKLEDRQTSW
KEEKNISFFILHFEPVLPNDNGSYRCSANFQSNLIESHSTTLYVT
>AJ717664|BTLA*01|Homo sapiens|F|EX3|
DVKSASERPSKDEMASRPWLLYSLLPLGGLPLLITTCFCLFCCLRRHQ
>AJ717664|BTLA*01|Homo sapiens|F|EX4|
GKQNELSDTAGREINL
>AJ717664|BTLA*01|Homo sapiens|F|EX5|
VDAHLKSEQTEASTRQNSQVLLSETGIYDNDPDLCFRMQEGSEVYSNPCLEENKPGIVYA
SLNHSVIGLNSRLARNVKEAPTEYASICVRS
>BTLA*01|Homo sapiens|F|EX1-5|
MKTLPAMLGTGKLFWVFFLIPYLDIWNIHGKESCDVQLYIKRQSEHSILAGDPFELECPV
KYCANRPHVTWCKLNGTTCVKLEDRQTSWKEEKNISFFILHFEPVLPNDNGSYRCSANFQ
SNLIESHSTTLYVTDVKSASERPSKDEMASRPWLLYSLLPLGGLPLLITTCFCLFCCLRR
HQGKQNELSDTAGREINLVDAHLKSEQTEASTRQNSQVLLSETGIYDNDPDLCFRMQEGS
EVYSNPCLEENKPGIVYASLNHSVIGLNSRLARNVKEAPTEYASICVRS