A cortical lectin from the oocytes of Rutilus rutilus stimulates mitogenic activity and release of soluble factors from human lymphocyte cultures and inhibits protein synthesis in a cell-free system.

1. A cortical granule lectin was isolated from vitellogenic oocytes of a bony fish, the roach Rutilus rutilus. 2. The lectin agglutinates human erythrocytes, is specific for L-rhamnose and is composed of different polypeptide subunits. 3. The lectin is the first lectin of animal origin that inhibits protein-synthesis by a rabbit reticulocyte lysate, and is also mitogenic for human lymphocytes.