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IMGT reference sequences in FASTA format:

Nucleotide 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) 
>J03857|CD79B*01|Mus musculus|F|EX1|
atggccacactggtgctgtcttccatgccctgccactggctgttgttcctgctgctgctc
ttctcag
>J03857|CD79B*01|Mus musculus|F|EX2|
gtgagccggtaccagcaatgacaagcagtgacctgccactgaatttccaag
>J03857|CD79B*01|Mus musculus|F|EX3|[D]|C-LIKE|
...............gaagcccttgttcccagatctggcagcacccgaggtttgcagcca
aaaagcgg.........agctccatggtgaagtttcactgctacacaaaccactcaggt.
..............gcactgacctggttccgaaagcgagggagccagcagccc.......
..caggaactggtctcagaagagggacgcattgtgcag..................accc
agaatggctctgtctacaccctcactatccaaaacatccagtac......gaggataatg
gtatctacttctgcaagcagaaatgtgacagc......gccaaccataatgtcaccgaca
gctgtggcacggaacttctagtcttag
>J03857|CD79B*01|Mus musculus|F|EX4|
gattcagcacgttggaccaactgaagcggcggaacacactgaaagatggcattatcttga
tccagaccctcctcatcatcctcttcatcattgtgcccatcttcctgctacttgacaag
>J03857|CD79B*01|Mus musculus|F|EX5|
gatgacggcaaggctgggatggaggaagatcacacctatgag
>J03857|CD79B*01|Mus musculus|F|EX6|
ggcttgaacattgaccagacagccacctatgaagacatagtgactcttcggacaggggag
gtaaagtggtcggtaggagagcatccaggccaggaa