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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) 
>AF142145|CTLA4*01|Mus musculus|F|EX1|
MACLGLRRYKAQLQLPSRTWPFVALLTLLFIPVFSE
>AF142145|CTLA4*01|Mus musculus|F|EX2|[D]|V-LIKE|
AIQVTQPSVVLASSHGVASFPCEYSPSHNTDEVRVTVLRQTNDQMTEVCATTFTEKNTVG
FLDYPFCSGTFNESRVNLTIQGLRAVDTGLYLCKVELMYPPPYFVGMGNGTQIYVI
>AF142145|CTLA4*01|Mus musculus|F|EX3|
DPEPCPDSDFLLWILVAVSLGLFFYSFLVTAVSLSKM
>AF142145|CTLA4*01|Mus musculus|F|EX4|
LKKRSPLTTGVYVKMPPTEPECEKQFQPYFIPIN
>CTLA4*01|Mus musculus|F|EX1-EX4|Splicing A|complete|
MACLGLRRYKAQLQLPSRTWPFVALLTLLFIPVFSEAIQVTQPSVVLASSHGVASFPCEY
SPSHNTDEVRVTVLRQTNDQMTEVCATTFTEKNTVGFLDYPFCSGTFNESRVNLTIQGLR
AVDTGLYLCKVELMYPPPYFVGMGNGTQIYVIDPEPCPDSDFLLWILVAVSLGLFFYSFL
VTAVSLSKMLKKRSPLTTGVYVKMPPTEPECEKQFQPYFIPIN*