Porcine VEG Proteins and Tear Prealbumins

Small soluble proteins, belonging to the lipocalin family are secreted in large amounts by tongue von Ebner's glands and lachrymal glands. In humans, the lingual protein, called VEG, and the lachrymal protein, called tear prealbumin, have shown identical cDNA sequences. In the pig, we have purified homodimeric proteins with subunits of 17 kDa, both from von Ebner's glands and from lachrymal glands. In both cases, the proteins can be resolved into two isoforms on a chromatofocusing column. Partial aminoacid sequences and full cDNA sequences have been obtained for the more abundant forms purified from both tissues. The two proteins appear to be identical, as in humans. The reason why the same protein is expressed in different tissues, as well as its physiological function, still remain to be clarified.