Seminal plasma proteins bind to the sperm surface at ejaculation and may modulate sperm properties during reproduction. DQH sperm surface protein shows affinity to oviductal epithelium and zona pellucida (ZP) glycoproteins. The mRNA transcript of DQH protein was found in seminal vesicles (SV). DQH was immunodetected by monoclonal antibodies (MAbs) in SV extract and fluid, on SV tissue sections and on the membrane-associated acrosome part of ejaculated spermatozoa. These results confirmed the ability of DQH protein to bind to the sperm surface at ejaculation and to participate in the formation of the sperm reservoir in the porcine oviduct. Moreover, monoclonal antibodies reduced binding of sperm to oocytes and proved the role of DQH protein in the sperm-ZP primary binding