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IMGT reference sequences in FASTA format:

Amino acid sequences with 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|
GKESCDVQLYIKRQSEHSILA..GDPFELECPVKYCA.....NRPHVTWCKLNGTTCVKL
E...DRQTSWKEEK..........NISFFILHFEPVLP....NDNGSYRCSANFQ...SN
LIESHSTTLYVT
>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
>DQ198368|BTLA*01|Homo sapiens|F|EX1|SplicingB|
MKTLPAMLGTGKLFWVFFLIPYLDIWNIH
>DQ198368|BTLA*01|Homo sapiens|F|EX2|[D]|C-LIKE|SplicingB|
GKESCDVQLYIKRQSEHSILA..GDPFELECPVKYCA.....NRPHVTWCKLNGTTCVKL
E...DRQTSWKEEK..........NISFFILHFEPVLP....NDNGSYRCSANFQ...SN
LIESHSTTLYVT
>DQ198368|BTLA*01|Homo sapiens|F|EX4|SplicingB|
GKQNELSDTAGREINL
>DQ198368|BTLA*01|Homo sapiens|F|EX5|SplicingB|
VDAHLKSEQTEASTRQNSQVLLSETGIYDNDPDLCFRMQEGSEVYSNPCLEENKPGIVYA
SLNHSVIGLNSRLARNVKEAPTEYASICVRS
>NM_181780|BTLA*02|Homo sapiens|F|EX1|
MKTLPAMLGTGKLFWVFFLIPYLDIWNIH
>NM_181780|BTLA*02|Homo sapiens|F|EX2|[D]|C-LIKE|
GKESCDVQLYIKRQSEHSILA..GDPFELECPVKYCA.....NRPHVTWCKLNGTTCVKL
E...DRQTSWKEEK..........NISFFILHFEPVLP....NDNGSYRCSANFQ...SN
LIESHSTTLYVT
>NM_181780|BTLA*02|Homo sapiens|F|EX3|
DVKSASERPSKDEMASRPWLLYSLLPLGGLPLLITTCFCLFCCLRRHQ
>NM_181780|BTLA*02|Homo sapiens|F|EX4|
GKQNELSDTAGREINL
>NM_181780|BTLA*02|Homo sapiens|F|EX5|
VDAHLKSEQTEASTRQNSQVLLSETGIYDNDPDLCFRMQEGSEVYSNPCLEENKPGIVYA
SLNHSVIGLNSRLARNVKEAPTEYASICVRS
>AK131204|BTLA*03|Homo sapiens|F|EX1|
MLGTGKLFWVFFLIPYLDIWNIH
>AK131204|BTLA*03|Homo sapiens|F|EX2|[D]|C-LIKE|
GKESCDVQLYIKRQSEHSILA..GDPFELECPVKYCA.....NRPHVTWCKLNGTTCVKL
E...DRQTSWKEEK..........NISFFILHFEPVLP....NDNGSYRCSANFQ...SN
LIESHSTTLYVT
>AK131204|BTLA*03|Homo sapiens|F|EX3|
DVKSASERPSKDEMASRPWLLYSLLPLGGLPLLITTCFCLFCCLRRHQ
>AK131204|BTLA*03|Homo sapiens|F|EX4|
GKQNELSDTAGREINL
>AK131204|BTLA*03|Homo sapiens|F|EX5|
VDAHLKSEQTEASTRQNSQVPLSETGIYDNDPDLCFRMQEGSEVYSNPCLEENKPGIVYA
SLNHSVIGLNSRLARNVKEAPTEYASICVRS
>AY293286|BTLA*04|Homo sapiens|F|EX1|
MKTLPAMLGTGKLFWVFFLIPYLDIWNIH
>AY293286|BTLA*04|Homo sapiens|F|EX2|[D]|C-LIKE|
GKESCDVQLYIKRQSEHSILA..GDPFELECPVKYCA.....NRPHVTWCKLNGTTCVKL
E...DRQTSWKEEK..........NISFFILHFEPMLP....NDNGSYRCSANFQ...SN
LIESHSTTLYVT
>AY293286|BTLA*04|Homo sapiens|F|EX3|
DVKGASERPSKDEVASRPWLLYSLLPLGGLPLLITTWFCLFCCLRRHQ
>AY293286|BTLA*04|Homo sapiens|F|EX4|
GKQNELSDTAGREINL
>AY293286|BTLA*04|Homo sapiens|F|EX5|
VDAHLKSEQTEASTRQNSQVLLSEAGIYDNDPDLCFRMQEGSEVCSNPCLEENKPGIVYA
SLNHSVIGLNSRLARNVKEAPTEYASICVRS