Antigenic variation can occur as a result of different VSG genes within the same expression site being expressed as proteins, or when the active expression site is silenced and another expression site is activated.
In Pneumocystis the single expression site determines the expressed variant.
Two independent T. brucei 221VP117 clones were generated which express two VSGs from the same VSG expression site.
One proteomic study has shown that in addition to the expression site APH_1221, full-length p44 genes can be expressed at their own loci, whereas silent p44 genes have to be recombined into the expression site for protein production [ 37].
Earlier, it has been shown that T. brucei can be genetically modified to express two VSGs from the telomere of the active VSG expression site [43].
The CRJE is present both at the expression site at the junction between the UCS and the expressed MSG gene, and in MSG genes that were not attached to the expression site (donor MSG genes).
In trout and mammals, the major extrahepatic expression site for CYP3A forms is in the intestine.
In this study, we identified a specific site in the genome of E. faecalis OG1RF that can serve as an expression site for a gene of interest.
Northern blotting by a CYP3A45-specific nucleotide probe showed that the major expression site was the intestinal ceca rather than the liver in both male and female trout.
One corresponded to the pilin encoding locus with the expression site and the silent loci.
To corroborate these findings, we further evaluated DRBP76 proteins in a major expression site, the CNS.
