Mapping of the N‑Linked Glycoproteome of Human Spermatozoa

N-Linked
glycosylation, a type of post-translational modification,
plays important roles in cell–cell recognition, adhesion, and
interactions. Although N-linked glycosylated proteins in sperm are
known to be important for gamete binding, little is known about the
composition of these proteins, particularly glycosylation sites, in
humans. In the present study, the use of glyco-FASP, coupled with
the tandem mass spectrometry (MS/MS) method, led to the identification
of 554 N-glycosylation sites and 297 N-glycosylated proteins in human
sperm. Bioinformatics analysis revealed enrichment of proteins with
functions in cell recognition and fertilization. Overall, about 91%
of the human sperm N-glycosylated proteins were classified into “membrane”,
“extracellular region”, and “lysosome”
groups, based on subcellular localization annotation. Furthermore,
glutathione peroxidase 4 (GPX4), a membrane glycoprotein identified
in our glycoproteome, was shown to play a significant role in gamete
interactions using the in vitro fertilization assay. Accordingly,
we propose that characterization of the human sperm glycoproteome
should effectively aid in clarifying the mechanisms of fertilization
and provide a valuable resource for the future development of male
contraceptives and diagnosis of male infertility.