BPIFB3 is annotated as a protein that may recognise and bind specific classes of odorants. It may act as a carrier molecule, transporting odorants across the mucus layer so that they can reach receptor sites. A second proposed role is in primary defence: recognising and removing potentially harmful odorants or pathogenic microorganisms from the mucosa, or clearing excess odorant from mucus so that new odorant stimuli can be received. These functions are described as possible rather than established.

The protein belongs to the BPI/LBP/Plunc superfamily and the BPI/LBP family, and the HGNC places the BPIFB3 gene in the BPI fold containing group. UniProt records it as both secreted and cytoplasmic. NCBI Gene summarises it as predicted to enable lipid binding activity and to be involved in the innate immune response, with a location in the cytoplasm. Mouse and rat both have an ortholog named Bpifb3.

The gene was previously designated chromosome 20 open reading frame 185 (C20orf185), and the literature also uses the names LPLUNC3, RYA3 and dJ726C3.4. Researchers studying BPIFB3 often do so alongside other BPI fold family members such as BPIFB1, to compare how these proteins contribute to mucosal biology and innate defence.