VHH(LaG-16) is a single-domain antibody fragment that binds the GFP fluorescent protein and some of its derivatives, including CFP, BFP, YFP, Emerald and EGFP. It does not bind 'DsRed', the naturally occurring fluorescent protein encoded by the Discosoma drFP583 gene, or its mCherry derivative. VHH(LaG-16) corresponds to the antigen-binding variable domain (VHH domain) of a heavy chain antibody originally isolated from a llama (Lama glama) immunized with purified GFP protein (PMID:25362362).