The virion's outer surface is covered with globular spikes, which are formed from glycoprotein, one of the virion's seven structural proteins and the only one of its proteins to be expressed on the outer surface.
While TGR5 is most highly expressed on the outer and inner nuclear membranes of the cholangiocyte intracellularly, one study noted that it could also be found in multivesicular bodies, intracellular vesicles and endoplasmic reticulum.
TSPO primarily is expressed on the outer mitochondrial membrane of microglia and reactive astrocytes, with low expression levels in other neuronal cells [8].
PET imaging of microglial cells in vivo involves utilising ligands labelled with 11C or 18F radioisotopes that bind translocator protein (TSPO) expressed on the outer mitochondrial membrane in microglia.
Due to the efficient concurrent binding of CFH and PLG to immobilized HcpA it is to be expected that both host proteins similarly bind to HcpA expressed on the outer surface of B. recurrentis.
Qualitatively the same result was obtained by analyzing chimeric VLPs in which the antigenic Δpp65 moiety was expressed on the outer VLP surface by in-frame insertion into surface-exposed loops of Gag immediately upstream of amino acid position S182 and flanked by flexible spacers (Powilleit and Schmitt, unpublished).
MAVS is ubiquitously expressed on the outer membrane of mitochondria.
These results suggest that the chimeric Anxa5-GPI protein is expressed on the outer leaflet of the plasma membrane.
For example, LPS is the pathogen-associated molecular pattern (PAMP) expressed on the outer membrane of gram-negative bacteria.
MOG is expressed on the outer surface of CNS myelin sheaths and comprises about 0.05% of total myelin protein [ 14].
Curli are a fairly recently identified class of bacterial filaments expressed on the outer surfaces of Enterobacteriaceae (Olsen et al, 1989; Barnhart and Chapman, 2006).
