Ran sticks a GEF to chromatin

Ran sticks a GEF to chromatin

A protease inhibitor unsticks cells AI-1 is unique among protease inhibitors because it binds to the matrix protein vitronectin (VN). PAI-1 binding blocks VN's binding site for the cell surface receptor uPAR and for integrin family members. Czekay et al. (page 781) now show that PAI-1 is also able to detach cells through a less direct approach. Unlike the direct competition method, PAI-1 also d...

Ran Binds to Chromatin by Two Distinct Mechanisms

Ran GTPase plays important roles in nucleocytoplasmic transport in interphase and in both spindle formation and nuclear envelope (NE) assembly during mitosis. The latter functions rely on the presence of high local concentrations of GTP-bound Ran near mitotic chromatin. RanGTP localization has been proposed to result from the association of Ran's GDP/GTP exchange factor, RCC1, with chromatin, b...

Cytomegalovirus sticks it to MHC

V iruses have numerous tricks for dodging the immune system. Stagg et al. reveal a key detail in one of these stratagems, identifying a protein that enables cyto-megalovirus to shut down an antiviral defense. Cytomegalovirus, which most people contract at some point in their lives, eludes immune system surveillance by targeting the protein MHC I. When we're sick, MHC I captures bits of viral pr...

Sticking with Carrots and Sticks (Sticking Points Aside): A Response to Ventakapuram, Goldberg, and Forrow

Ran

How is Ran involved in nuclear transport? Cargo is transported through pores in the nuclear envelope, in association with carriers that bind to pore proteins called nucleoporins. A Ran–GTP gradient across the envelope is created by the asymmetric distribution of the GTPase activating protein known as RanGAP, which is in the cytosol, and of the guanine nucleotide exchange factor RanGEF in the nu...