SAMHD1's protein expression profile in humans.

The deoxynucleoside triphosphate triphosphohydrolase and 3' → 5' exonuclease SAMHD1 restricts HIV-1 infection in noncycling hematopoietic cells in vitro, and SAMHD1 mutations are associated with AGS. Little is known about the in vivo expression and functional regulation of this cellular factor. Here, we first assessed the SAMHD1 protein expression profile on a microarray of 25 human tissues from >210 donors and in purified primary cell populations.

SAMHD1 restricts HIV-1 infection in resting CD4(+) T cells.

Unlike activated CD4(+) T cells, resting CD4(+) T cells are highly resistant to productive HIV-1 infection. Early after HIV-1 entry, a major block limits reverse transcription of incoming viral genomes. Here we show that the deoxynucleoside triphosphate triphosphohydrolase SAMHD1 prevents reverse transcription of HIV-1 RNA in resting CD4(+) T cells.

MUF1/leucine-rich repeat containing 41 (LRRC41), a substrate of RhoBTB-dependent cullin 3 ubiquitin ligase complexes, is a predominantly nuclear dimeric protein.

RhoBTB (BTB stands for broad-complex, tramtrack, bric à brac) proteins are tumor suppressors involved in the formation of cullin 3 (Cul3)-dependent ubiquitin ligase complexes. However, no substrates of RhoBTB-Cul3 ubiquitin ligase complexes have been identified. We identified MUF1 (LRRC41, leucine-rich repeat containing 41) as a potential interaction partner of RhoBTB3 in a two-hybrid screening on a mouse brain cDNA library.

Rho GTPases of the RhoBTB subfamily and tumorigenesis.

RhoBTB proteins constitute a subfamily of atypical members within the Rho family of small guanosine triphosphatases (GTPases). Their most salient feature is their domain architecture: a GTPase domain (in most cases, non-functional) is followed by a prolinerich region, a tandem of 2 broadcomplex, tramtrack, bric a brac (BTB) domains, and a conserved Cterminal region. In humans, the RhoBTB subfamily consists of 3 isoforms: RhoBTB1, RhoBTB2, and RhoBTB3.