spGFP1-10 corresponds to the N-terminal 124 amino acid residues of the sfGFP fluorescent protein, which make up 10 of the 11 strands of the GFP β-barrel structure. The sequence has been further mutated relative to sfGFP to be stable as a protein fragment. If the spGFP1-10 split fluorescent fragment is brought together with a complementary split fluorescent fragment (e.g. spGFP11) in vivo, a functional fluorescent protein may be reconstituted. spGFP1-10 is designed for use in the 'GFP Reconstitution Across Synaptic Partners' (GRASP) technique (PMID:18255029), to study connectivity in the nervous system.