AQP4-P construct and mutations. (A) Cartoon of the fusion protein, AQP4-P, which contains the first 46 amino acids of human AQP4, a two-residue Val-Thr linker, and amino acids 88–229 of bovine prolactin (Shi et al. 1995). Codon 44 (Leu44) was mutated to an amber (TAG), opal (TGA), ochre (TAA) stop codon, or to Cys (TGC) as indicated. In the L44C mutant the endogenous Cys at residue 49 was also converted to Ala (C49A). For dual probe incorporation, amber and opal stop codons were simultaneously placed at residues Leu44 and His68, respectively. Where indicated, mRNA was truncated at codon 183 (B) or codon 98 (C) to generate the constructs AQP4-P(183) and AQP4-P(98), respectively. Full-length plasmids encode TAA at codon 191 and TGA at codon 200. Residues are numbered sequentially from Met1.
