Isolation and sequence of a cDNA coding for the heavy chain constant region of IgG from the Australian brushtail possum, Trichosurus vulpecula

A brushtail possum (Trichosurus vulpecula) mesenteric lymph node cDNA libra ry was screened with a South American short-tailed opossum (Monodelphis dom estica) immunoglobulin gamma heavy chain constant region (Cy) probe, result ing in the isolation of a 1518 nucleotide cDNA clone. The sequence correspo nds to exons 1-3 of C gamma. The Australian marsupial (T. vulpecula) sequen ce is 70% identical at the amino acid level with the American marsupial (M. domestica) sequence, but less similar to the eutherian mammals (45-50%). T hese data provide the opportunity to compare the evolution of IgG between o rders of marsupials separated by at least 75 million years and confirm the appearance of IgG prior to the metatherian/eutherian divergence. (C) 1999 E lsevier Science Ltd. All rights reserved.