Glycosylation of multi-TM proteins. (A) The Δlog₂ values for sites located in loops (L) or N- or C-terminal tails (N- or C-tails, respectively) of multi-TM proteins in STT3A^−/− cells. Sites in N-terminal tails are enriched in the negative zone (inset, Δlog₂ < −1). (B) The Δlog₂ values for sites in the N-terminal tails are plotted versus tail length (log₁₀) and color-coded for sequon type (NXT vs. NXS). (C) The Δlog₂ values for sites located in loops or in N- or C-terminal tails of multi-TM proteins in STT3B^−/− cells. (D) The Δlog₂ values for sites located in loops are plotted versus the distance between the sequon and the closest TM span and color-coded for sequon type (NXT vs. NXS) and number of TM spans. Most of the affected sites (Δlog₂ < −1) in proteins with more than five TM spans are located in the first lumenal loop of the protein (see inset). For proteins with more than three lumenal loops, the middle (mid.) category includes all lumenal loops except the first and last. (A and C) The number of sites (Δlog₂ < −1) and proteins from which they are derived is shown.