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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) 
>AF411058|ICOS*01|Homo sapiens|F|EX1|
MKSGLWYFFLFCLRIKVLT
>AF411058|ICOS*01|Homo sapiens|F|EX2|[D]|V-LIKE|
GEINGSANYEMFIFHNGGVQILCKYPDIVQQFKMQLLKGGQILCDLTKTKGSGNTVSIKS
LKFCHSQLSNNSVSFFLYNLDHSHANYYFCNLSIFDPPPFKVTLTGGYLHIY
>AF411058|ICOS*01|Homo sapiens|F|EX3|
ESQLCCQLKFWLPIGCAAFVVVCILGCILICWLTKK
>AF411058|ICOS*01|Homo sapiens|F|EX4|
KYSSSVHDPNGEYMFMRAVNTAKKSRLT
>AF411058|ICOS*01|Homo sapiens|F|EX5|
DVTL
>ICOS*01|Homo sapiens|F|EX1-EX5|Splicing A|complete|
MKSGLWYFFLFCLRIKVLTGEINGSANYEMFIFHNGGVQILCKYPDIVQQFKMQLLKGGQ
ILCDLTKTKGSGNTVSIKSLKFCHSQLSNNSVSFFLYNLDHSHANYYFCNLSIFDPPPFK
VTLTGGYLHIYESQLCCQLKFWLPIGCAAFVVVCILGCILICWLTKKKYSSSVHDPNGEY
MFMRAVNTAKKSRLTDVTL*
>BC028006|ICOS*01|Homo sapiens|F|EX1|Splicing B|
MKSGLWYFFLFCLRIKVLT
>BC028006|ICOS*01|Homo sapiens|F|EX2|[D]|V-LIKE|Splicing B|
GEINGSANYEMFIFHNGGVQILCKYPDIVQQFKMQLLKGGQILCDLTKTKGSGNTVSIKS
LKFCHSQLSNNSVSFFLYNLDHSHANYYFCNLSIFDPPPFKVTLTGGYLHIY
>BC028006|ICOS*01|Homo sapiens|F|EX3|Splicing B|
ESQLCCQLKFWLPIGCAAFVVVCILGCILICWLTKKM
>ICOS*01|Homo sapiens|F|EX1-EX3|Splicing A|complete|
MKSGLWYFFLFCLRIKVLTGEINGSANYEMFIFHNGGVQILCKYPDIVQQFKMQLLKGGQ
ILCDLTKTKGSGNTVSIKSLKFCHSQLSNNSVSFFLYNLDHSHANYYFCNLSIFDPPPFK
VTLTGGYLHIYESQLCCQLKFWLPIGCAAFVVVCILGCILICWLTKKM*