Characterization of amalgam: a member of the immunoglobulin superfamily from Drosophila.

The immunoglobulin superfamily is a diverse group of proteins that are involved in various aspects of cell surface recognition. Here, we report the characterization of amalgam (ama), a gene in the Antennapedia complex (ANT-C) of D. melanogaster that exhibits amino acid similarity to vertebrate neural cell adhesion molecules and other members of the immunoglobulin superfamily. The putative 333 amino acid ama protein consists of a signal sequence, three immunoglobulin-like domains, and a short slightly hydrophobic carboxy-terminal region. Antibodies against the ama protein reveal that it accumulates on the surface of various mesodermal and neural cells during embryogenesis. The function of this protein remains elusive, as no mutations have been recovered for ama during saturation EMS mutagenesis of this chromosomal region.