Butyrophilin

Butyrophilins are membrane proteins belonging to the immunoglobulin superfamily (Ig).^[1][2] Butyrophilin (Btn) genes constitute a subgroup of at least 10 genes in the Ig superfamily identified in human, mouse, cow, goat and other species.^[3]

Butyrophilin
Identifiers
Symbol	Butyrophilin
Membranome	14

Butyrophilin, subfamily 1, member A1
Identifiers
Symbol	BTN1A1
NCBI gene	696
HGNC	1135
RefSeq	NP_001723
UniProt	Q13410
Other data
Locus	Chr. 6 p22.2
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Butyrophilin, subfamily 2, member A2
Identifiers
Symbol	BTN2A2
NCBI gene	10385
HGNC	1137
RefSeq	NP_008926
UniProt	Q8WVV5
Other data
Locus	Chr. 6 p22.2
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Butyrophilin, subfamily 3, member A1
Identifiers
Symbol	BTN3A1
NCBI gene	11119
HGNC	1138
RefSeq	NP_008979
UniProt	O00481
Other data
Locus	Chr. 6 p22.2
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The eponymous Btn gene (BTN1A1 in humans; Btn1a1 in mouse) is highly expressed in the secretory epithelium of the mammary gland during lactation. Other homologues are predominantly expressed in skeletal muscle and the intestine and erythroid cells. In contrast, BTN2A1 and 2 and BTN3A1, 2, and 3 are widely expressed in many tissues, suggesting that the structural domains of Btn proteins may have both universal and tissue-specific functions.

Types include:

• BTN1A1 - Regulates secretion of milk-lipid droplets
• BTN2A2 - Involved in lipid, fatty-acid, and sterol metabolism
• BTN3A1 - Presents phosphoantigens to Gamma delta T cells