Interaction analysis identifies semenogelin I fragments as new binding partners of PIP in human seminal plasma

► Co-immunoprecipitation of PIP interacting proteins from human seminal plasma. ► Separation of proteins by gel electrophoresis and identification by MALDI-TOF/MS. ► Three interacting partners for PIP were identified, viz. ZAG, HAS and SEG1 fragments. ► First report of PIP interacting with SEG1 fragments. ► Possible role toward helping spermatozoa to acquire their motility.