13xlexAop regulatory sequences drive expression of 'pre-mGRASP'. pre-mGRASP (PMID:22138823) is composed of an N-terminal signal peptide, the spGFP11 split fluorescent protein fragment, the extracellular and transmembrane domains of the human CD4 gene and an intracellular domain that targets the protein to presynaptic sites (Tag:TS(rNrxn1-β)).