Localization and identification of sumoylated proteins in human sperm: excessive sumoylation is a marker of defective spermatozoa.

Background: Sumoylation is a type of post-translational modification that is implicated in the regulation of numerous cellular events. However, its role in the function of human sperm has not yet been characterized.

Methods And Results: In this study, both immunofluorescence and electron microscopy revealed that small ubiquitin-like modifiers (SUMO) SUMO1 and SUMO2/3 were highly enriched in the neck area of human sperm that is associated with the redundant nuclear envelope and were also detectable in the flagella and some head regions.