SCAM of select TM3 residues using a large MTS reagent shows no evidence of reactivity. Shown is an alignment of Cx32, Cx46 and Cx50 sequence from the CL/TM3 border through the proximal portion of E2. Residues indicated by arrows in Cx32 were reported to be pore-lining in Cx32 GJ channels (Skerrett et al., 2002). Boxed residues in Cx46 and Cx50 were subjected to SCAM analysis using MTS biotin-X. These include Y155, I159, F161, V167, F169 and A171 in Cx46 and Y158, V170 and F172 in Cx50. No effects were observed at any of these positions.