Specific detection of ERV-K-(HML-2) Gag in brain samples derived from macaques and humans. Extracts from the frontal/parietal cortex region of M. fascicularis and H. sapiens, respectively, and lysates from Tera-1 cells (kindly provided by Dr. J. Mayer) were separated by PAGE and blotted to PVDF membrane. Detection was performed with polyclonal antibody K2548 (left panel), pre-immune serum (middle) or by omission of the primary antibody (right panel), respectively. Predominant HERV-K-(HML-2) Gag immunoreactivity was detected at 70, 80 and 105 kDa, but was absent in the pre-immune and secondary antibody controls. Molecular weight marker bands are indicated at the right.