Established and putative isoforms of human G6b. The main structural features are shown, including the IgV domain, ITIM, ITSM, and PRR. G6b-A and -B contain transmembrane regions and are therefore represented as surface receptors. G6b-C, -D, and -E, identified in transcriptome analysis but not as expressed protein, are predicted to be secreted because they lack the transmembrane domain. Residues are numbered according to mature human peptide sequences, after cleavage of the signal peptide. Professional illustration by Patrick Lane, ScEYEnce Studios.