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. Author manuscript; available in PMC: 2012 Sep 15.
Published in final edited form as: J Immunol. 2012 Feb 15;188(6):2794–2804. doi: 10.4049/jimmunol.1102068

Figure 8. Postulated sequential topogenesis and processing of the SP UL40.

Figure 8

Upon targeting and translocation, the gpUL40 precursor (pre-gpUL40) is cleaved by SPase. The liberated SP (SPUL40) remains anchored in the membrane. Proposed association of the hydrophobic N-terminal segment (yellow box labeled *) with the membrane, and subsequent flipping of the hydrophilic spacer (green) and the c-region (blue) are indicated. The canonical n- and h-region are indicted in yellow (h) and red (n), respectively. In semi-intact cells, SPUL40 is further processed by an SPP-type intramembrane protease. The consensus HLA-E-binding peptide is delivered to the ER in a TAP-independent manner, where it binds and stabilizes both endogenous HLA-E and the HCMV-encoded MHC-I homologue gpUL18.