Immunoglobulin of the toadfish, Spheroides glaber.

The major serum immunoglobulin of the toadfish, Spheroides glaber, was shown to be a tetrameric IgM-like molecule of probable structure (mu2L2)4. The tetrameric molecule could be dissociated, without reduction, into dimeric and monomeric forms. A low molecular weight immunoglobulin present at levels of about one twentieth of those of the high molecular weight IgM was detected in serum.