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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) 
>AF327184|ICOS*01|Mus musculus|F|EX1|
MKPYFCRVFVFCFLIRLLT
>AF327185|ICOS*01|Mus musculus|F|EX2|[D]|V-LIKE|
GEINGSADHRMFSFHNGGVQISCKYPETV.......QQLKMRLFR..EREVLCELTKTK.
GSGNAVSIKNP....MLCLYHLSNNSVSFFLNNPDSSQGSYYFCSLSIFDPPPFQERNLS
GGYLHIY
>AF327185|ICOS*01|Mus musculus|F|EX3|
ESQLCCQLKLWLPVGCAAFVVVLLFGCILIIWFSKK
>AF327185|ICOS*01|Mus musculus|F|EX4|
KYGSSVHDPNSEYMFMAAVNTNKKSRLA
>AF327185|ICOS*01|Mus musculus|F|EX5|
GVTS
>AL645744|ICOS*01|Mus musculus|F|EX1|splicing B|
MKPYFCRVFVFCFLIRLLT
>AL645744|ICOS*01|Mus musculus|F|EX2|[D]|V-LIKE|splicing B|
GEINGSADHRMFSFHNGGVQISCKYPETV.......QQLKMRLFR..EREVLCELTKTK.
GSGNAVSIKNP....MLCLYHLSNNSVSFFLNNPDSSQGSYYFCSLSIFDPPPFQERNLS
GGYLHIY
>AL645744|ICOS*01|Mus musculus|F|EX3|splicing B|
ESQLCCQLKLWLPVGCAAFVVVLLFGCILIIWFSKK
>AL645744|ICOS*01|Mus musculus|F|EX4|splicing B|
KYGSSVHDPNSEYMFMAAVNTNKKSRLAGTAPLTALGREEHTSWLRLELICLFLF
>AF257230|ICOS*02|Mus musculus|F|EX1|
MKPYFCHVFVFCFLIRLLT
>AF257230|ICOS*02|Mus musculus|F|EX2|[D]|V-LIKE|
GEINGSADHRMFSFHNGGVQISCKYPETV.......QQLKMRLFR..EREVLCELTKTK.
GSGNAVSIKNP....MLCLYHLSNNSVSFFLNNPDSSQGSYYFCSLSIFDPPPFQERNLS
GGYLHIY
>AF257230|ICOS*02|Mus musculus|F|EX3|
ESQLCCQLKLWLPVGCAAFVVVLLFGCILIIWFSKK
>AF257230|ICOS*02|Mus musculus|F|EX4|
KYGSSVHDPNSEYMFMAAVNTNKKSRLA
>AF257230|ICOS*02|Mus musculus|F|EX5|
GVTS