Am. Colberg-poley et al., Human cytomegalovirus UL37 immediate-early regulatory proteins traffic through the secretory apparatus and to mitochondria, J GEN VIROL, 81, 2000, pp. 1779-1789
The human cytomegalovirus (HGMV) UL36-38 immediate-early (IE) locus encodes
the UL37 exon 1 (pUL37x1) and UL37 (gpUL37) regulatory proteins, which hav
e anti-apoptotic activities. pUL37x1 shares its entire sequence, including
a hydrophobic leader and an acidic domain, with the exception of one residu
e, with the amino terminus of gpUL37, gpUL37 has, in addition, unique N-lin
ked glycosylation, transmembrane and cytosolic domains. A rabbit polyvalent
antiserum was generated against residues 27-40 in the shared amino-termina
l domain and a mouse polyvalent antiserum was generated against the full-le
ngth protein to study trafficking of individual UL37 proteins in human cell
s that transiently expressed gpUL37 or pUL37x1, Go-localization studies by
confocal laser scanning microscopy detected trafficking of gpUL37 and pUL37
x1 from the endoplasmic reticulum to the Golgi apparatus in permissive U373
cells and in human diploid fibroblasts (HFF), Trafficking of gpUL37 to the
cellular plasma membrane was detected in unfixed HFF cells. FLAG-tagged gp
UL37 trafficked similarly through the secretory apparatus to the plasma mem
brane. By using confocal microscopy and immunoblotting of fractionated cell
s, gpUL37 and pUL37x1 were found to co-localize with mitochondria in human
cells. This unconventional dual trafficking pattern through the secretory a
pparatus and to mitochondria is novel for herpesvirus IE regulatory protein
s.