A novel export pathway

The lectin galectin-1 is exported from cells via a poorly characterized secretory pathway. On page 373, Seelenmeyer et al. demonstrate that the cell surface receptors to which the lectin binds on the exterior of the cell are also required for export of the glycoprotein from the interior.

Galectin-1 interacts with β-galactoside–containing sugar moieties on extracellular matrix and cell surface receptors. Based on previous work, researchers think galectin-1 is translated and folded in the cytoplasm before localizing to the inside of the plasma membrane and being exported.

Seelenmeyer et al. found that galectin-1 mutants deficient for binding to β-galactoside get stuck in the cytoplasm and are not exported. Moreover, cells that cannot produce the cell surface receptors that bind galectin-1 failed to export wild-type galectin-1. The fungal lectin CGL2, which resembles galectin-1 in its folded shape, was...