Full-length Tau-YFP binds microtubules while MTBR-YFP aggregates in
C17.2 neural cells. A, Tau constructs. YFP fusion proteins were
created for expression in mammalian cells as follows: full-length Tau (441
amino acids), Tau-YFP, the microtubule-binding region, MTBR-YFP. For bacterial
expression, we used either MTBR alone or with a C-terminal hemagglutinin tag,
MTBR-HA. B, Tau-YFP co-localizes with tubulin when transfected into
C17.2 cells. C, MTBR-YFP does not co-localize with tubulin and
spontaneously aggregates when transfected into C17.2 cells. D,
Western blot showing similar expression levels of Tau-YFP and MTBR-YFP. Blots
were probed with GFP and actin antibodies. E, based on counting
transfected cells, 6% of cells have spontaneous aggregation of Tau-YFP,
whereas 79% of cells have spontaneous aggregation of MTBR-YFP (n = 4,
100 transfected cells counted per experiment). F, 83% of cells have
Tau-YFP that co-localizes with tubulin, whereas 3.5% of cells have MTBR-YFP
that co-localizes with tubulin (n = 4, 100 transfected cells counted
per experiment). Scale bars, 10 μm.