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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) 
>AF142145|CTLA4*01|Mus musculus|F|EX1|
MACLGLRRYKAQLQLPSRTWPFVALLTLLFIPVFSE
>AF142145|CTLA4*01|Mus musculus|F|EX2|[D]|V-LIKE|
AIQVTQPSV.VLASSHGVASFPCEYSPSHNT...DEVRVTVLRQTNDQMTEVCATTFTE.
.KNTVGFLDYP.....FCSGTFNESRVNLTIQGLRAVDTGLYLCKVELMYPPPYFVGMGN
GTQIYVI
>AF142145|CTLA4*01|Mus musculus|F|EX3|
DPEPCPDSDFLLWILVAVSLGLFFYSFLVTAVSLSKM
>AF142145|CTLA4*01|Mus musculus|F|EX4|
LKKRSPLTTGVYVKMPPTEPECEKQFQPYFIPIN
>X05719|CTLA4*02|Mus musculus|F|EX1|
MACLGLRRYKAQLQLPSRTWPFVALLTLLFIPVFSE
>X05719|CTLA4*02|Mus musculus|F|EX2|[D]|V-LIKE|
AIQVTQPSV.VLASSHGVASFPCEYSPSHNT...DEVRVTVLRQTNDQMTEVCATTFTE.
.KNTVGFLDYP.....FCSGTFNESRVNLTIQGLRAVDTGLYLCKVELMYPPPYFVGMGN
GTQIYVI
>X05719|CTLA4*02|Mus musculus|F|EX3|
DPEPCPDSDFLLWILVAVSLGLFFYSFLVSAVSLSKM
>X05719|CTLA4*02|Mus musculus|F|EX4|
LKKRSPLTTGVYVKMPPTEPECEKQFQPYFIPIN
>BC052683|CTLA4*03|Mus musculus|F|EX1|
MACLGLRRYKAQLQLPSRTWPFVALLTLLFIPVFSE
>BC052683|CTLA4*03|Mus musculus|F|EX2|[D]|V-LIKE|
AIQVTQPSV.VLASSHGVASFPCEYSPSHNT...DEVRVTVLRQTNDQMTEVCATTFTE.
.KNTVGFLDYP.....FCSGTFNESRVNLTIQGLRAVDTGLYLCKVELMYPPPYFVGMGN
GTQIYVI
>BC052683|CTLA4*03|Mus musculus|F|EX3|
DPEPCPDSDFLLWILVAVSLGLFFYSFLVTAVSLSKM
>BC052683|CTLA4*03|Mus musculus|F|EX4|
LKKRSPLTTGVYVKMPPTEPECEKQFQPYFIPIN