XENOPUS-LAEVIS L-14 LECTIN IS EXPRESSED IN A TYPICAL PATTERN IN THE ADULT, BUT IS ABSENT FROM EMBRYONIC-TISSUES

Soluble, dimeric, lactose-binding lectins with subunit Mr of similar t o 14-16 x 10(3), here called L-14s, are expressed in multiple tissues in all vertebrates that have been examined. L-14s have particular affi nity for polylactosamine chains on laminin, co-localize with laminin i n some basement membranes, and influence adhesion to laminin and proli feration for some cultured cells. In previous studies of mammals and c hickens, L-14s have been found at high levels in a variety of adult ti ssues, such as muscle and peripheral nerve, but at much higher levels in many embryonic tissues, suggesting a special role in development. T o further explore possible roles of L-14 in embryogenesis, we have stu died the expression of L-14 in embryonic and adult Xenopus laevis tiss ues. Except for the abundant L-14 in poison glands in adult Xenopus sk in, we find that Xenopus L-14 is expressed in the same general distrib ution as its mammalian homologues. However, we could detect no express ion of L-14 in Xenopus embryos using either a sensitive immunoassay fo r the protein or a sensitive RNase protection assay for its mRNA. Furt hermore, use of affinity chromatography to identify other lactose-bind ing lectins in embryonic tissue revealed only scarce proteins with hig her subunit molecular weights. These results suggest that in X.laevis L-14 functions in adult tissues and is not involved in embryogenesis.