Previous Article | Next Article ![]()
Mol. Cell. Biol., Aug 1996, 4207-4214, Vol 16, No. 8
HP Bogerd, RA Fridell, RE Benson, J Hua and BR Cullen
The Rex protein of human T-cell leukemia virus type 1, like the
functionally equivalent Rev protein of human immunodeficiency virus type 1,
contains a leucine-rich activation domain that specifically interacts with
the human nucleoporin-like Rab/hRIP cofactor. Here, this Rex sequence is
shown to function also as a protein nuclear export signal (NES). Rex
sequence libraries containing randomized forms of the activation domain/NES
were screened for retention of the ability to bind Rab/hRIP by using the
yeast two-hybrid assay. While the selected sequences differed widely in
primary sequence, all were functional as Rex activation domains. In
contrast, randomized sequences that failed to bind Rab/hRIP lacked Rex
activity. The selected sequences included one with homology to the Rev
activation domain/NES and a second that was similar to the NES found in the
cellular protein kinase inhibitor alpha. A highly variant, yet fully
active, activation domain sequence selected on the basis of Rab/hRIP
binding retained full NES function even though this sequence preserved only
a single leucine residue. In contrast, nonfunctional activation domain
mutants that were unable to bind Rab/hRIP had also lost NES function. These
data demonstrate that NES activity is a defining characteristic of the
activation domains found in the Rev/Rex class of retroviral regulatory
proteins and strongly support the hypothesis that the Rab/hRIP cofactor
plays a critical role in mediating the biological activity of these NESs.
In addition, these data suggest a consensus sequence for NESs of the
Rev/Rex class.
Copyright © 1996, American Society for Microbiology
Protein sequence requirements for function of the human T-cell leukemia virus type 1 Rex nuclear export signal delineated by a novel in vivo randomization-selection assay
Howard Hughes Medical Institute and Department of Genetics, Duke University Medical Center, Durham, North Carolina 27710, USA.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»