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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) 
>M74363|CTLA4*01|Homo sapiens|F|EX1|
MACLGFQRHKAQLNLATRTWPCTLLFFLLFIPVFCK
>M37243|CTLA4*01|Homo sapiens|F|EX2|[D]|V-LIKE|
AMHVAQPAV.VLASSRGIASFVCEYASPGKA...TEVRVTVLRQADSQVTEVCAATYMM.
.GNELTFLDDS.....ICTGTSSGNQVNLTIQGLRAMDTGLYICKVELMYPPPYYLGIGN
GTQIYVI
>M37244|CTLA4*01|Homo sapiens|F|EX3|
DPEPCPDSDFLLWILAAVSSGLFFYSFLLTAVSLSKM
>M37245|CTLA4*01|Homo sapiens|F|EX4|
LKKRSPLTTGVYVKMPPTEPECEKQFQPYFIPIN
>AC010138|CTLA4*02|Homo sapiens|F|EX1|
MACLGFQRHKAQLNLATRTWPCTLLFFLLFIPVFCK
>AC010138|CTLA4*02|Homo sapiens|F|EX2|[D]|V-LIKE|
AMHVAQPAV.VLASSRGIASFVCEYASPGKA...TEVRVTVLRQADSQVTEVCAATYMM.
.GNELTFLDDS.....ICTGTSSGNQVNLTIQGLRAMDTGLYICKVELMYPPPYYLGIGN
GTQIYVI
>AC010138|CTLA4*02|Homo sapiens|F|EX3|
DPEPCPDSDFLLWILAAVSSGLFFYSFLLTAVSLSKM
>AC010138|CTLA4*02|Homo sapiens|F|EX4|
LKKRSPLTTGVYVKMPPTEPECEKQFQPYFIPIN
>AF411058|CTLA4*03|Homo sapiens|F|EX1|
MACLGFQRHKAQLNLAARTWPCTLLFFLLFIPVFCK
>AF411058|CTLA4*03|Homo sapiens|F|EX2|[D]|V-LIKE|
AMHVAQPAV.VLASSRGIASFVCEYASPGKA...TEVRVTVLRQADSQVTEVCAATYMM.
.GNELTFLDDS.....ICTGTSSGNQVNLTIQGLRAMDTGLYICKVELMYPPPYYLGIGN
GTQIYVI
>AF411058|CTLA4*03|Homo sapiens|F|EX3|
DPEPCPDSDFLLWILAAVSSGLFFYSFLLTAVSLSKM
>AF411058|CTLA4*03|Homo sapiens|F|EX4|
LKKRSPLTTGVYVKMPPTEPECEKQFQPYFIPIN