A process in which a protein is transported to, or maintained in, a location within a presynapse. [ http://purl.obolibrary.org/obo/go/references/0000087 http://www.ncbi.nlm.nih.gov/pubmed/24449494 GOC:TermGenie ]
Synonyms: protein localization in presynapse protein localisation to presynapse protein localisation in presynapse recruitment of presynaptic proteins