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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) 
>M74363|CTLA4*01|Homo sapiens|F|EX1|
MACLGFQRHKAQLNLATRTWPCTLLFFLLFIPVFCK
>M37243|CTLA4*01|Homo sapiens|F|EX2|[D]|V-LIKE|
AMHVAQPAVVLASSRGIASFVCEYASPGKATEVRVTVLRQADSQVTEVCAATYMMGNELT
FLDDSICTGTSSGNQVNLTIQGLRAMDTGLYICKVELMYPPPYYLGIGNGAQIYVI
>M37244|CTLA4*01|Homo sapiens|F|EX3|
DPEPCPDSDFLLWILAAVSSGLFFYSFLLTAVSLSKM
>M37245|CTLA4*01|Homo sapiens|F|EX4|
LKKRSPLTTGVYVKMPPTEPECEKQFQPYFIPIN
>CTLA4*01|Homo sapiens|F|EX1-EX4|Splicing A|complete|
MACLGFQRHKAQLNLATRTWPCTLLFFLLFIPVFCKAMHVAQPAVVLASSRGIASFVCEY
ASPGKATEVRVTVLRQADSQVTEVCAATYMMGNELTFLDDSICTGTSSGNQVNLTIQGLR
AMDTGLYICKVELMYPPPYYLGIGNGAQIYVIDPEPCPDSDFLLWILAAVSSGLFFYSFL
LTAVSLSKMLKKRSPLTTGVYVKMPPTEPECEKQFQPYFIPIN*