S. Reiszporszasz et al., INVESTIGATION ON THE POTENTIAL ROLE OF THE AH RECEPTOR NUCLEAR TRANSLOCATOR PROTEIN IN VITAMIN-D RECEPTOR ACTION, Journal of receptor research, 13(8), 1993, pp. 1147-1159
The Ah receptor nuclear translocator protein (ARNT) is required for bi
nding of the Ah (dioxin) receptor to the xenobiotic responsive element
(XRE), and is a structural component of the XRE-binding form of the A
h receptor. The vitamin D receptor requires an accessory protein for b
inding to the vitamin D responsive element (VDRE) in the osteocalcin g
ene. Since the vitamin D receptor has similarities to the Ah receptor,
we investigated whether ARNT is also required for vitamin D receptor
activity. Two lines of evidence demonstrate that ARNT is not required
for vitamin D receptor activity, and therefore does not correspond to
the vitamin D receptor accessory protein: i) Antibodies to ARNT have n
o effect on binding of the vitamin D receptor to the VDRE. ii) c4, a m
utant of Hepa-1 cells that is defective in ARNT activity, and in which
binding of the Ah receptor to the XRE does not occur, possesses a vit
amin D receptor with full activity for binding the VDRE.