Gellular transport

Nuclear pores are plugged with a protein gel, say Steffen Frey, Ralf Richter, and Dirk Görlich (Universität Heidelberg, Germany). The researchers succeeded in forming the gel in vitro and believe that in vivo it forms a hydrophobic mesh—a mesh that can be breached only by small proteins or by the hydrophobic nuclear transport receptors (NTRs) that escort larger proteins in and out of the nucleus.

The group focused on the Phe and Gly (FG)-rich repeats present in many nuclear pore proteins. The effective concentration of the repeat proteins in the pore is close to 100 mg/ml. “At such a concentration, a gel must form,” says Görlich.

But proving that in vitro was not easy. Agarose makes a gel, but only if the powder is first boiled with water to make a homogeneous solution....