PDC-109 is a 13 kDa glycoprotein and the major phosphorylcholine- and heparin-binding protein of bull seminal plasma. It is built by an acidic 23-residue N-terminal sequence followed by a tandem of fibronectin type II domains. Full-length PDC-109 was crystallized in complex with o-phosphorylcholine by vapor diffusion in sitting drops. Crystals grew to maximal size of 0.5 x 0.3 x 0.2 mm3, diffract x-rays beyond 2.6 A resolution, and belong to space group P321 with unit cell dimensions a = b = 93.6 A, c = 52.7 A.