Figure 1. Schematic representation of the GUCY2D (RetGC1) primary structure [5,6]. The S248W missense mutation is located in the extracellular domain, and the R1091x truncation is located near the C-terminus, downstream of the catalytic domain. LP = leader peptide; ECD = extracellular domain; TM = transmembrane domain; KHD = kinase homology domain; DD = dimerization domain; CAT = catalytic domain.