[Characterizing the CD3 epsilon chain from the New World primate Aotus nancymaae].

Introduction: The T-cell receptor (TCR)-associated complex, CD3 (d, g, e) and z-chains are essential transmembrane proteins for signal transduction during T cell activation and immune response, as well as during thymocyte development.

Objective: This work established the CD3epsilon-chain primary structure for the New World owl monkey Aotus nancymaae.

Materials And Methods: Total RNA was isolated from peripheral blood mononuclear cells; CD3epsilon molecule was amplified, cloned and sequenced.

Results: The CD3epsilon amino acid sequence was deduced for the owl monkey Aotus nancymaae.> It has an identity for nucleotide and amino acid sequences with the human counterpart of 84% and 76%, respectively. As described in other species, the Aotus CD3-e molecule is very variable in the extracellular region and greatly conserved in the intracellular domain. Even though high variability occurs in the CD3epsilon-extracellular domain, the subregions involved in ectodomain folding are conserved.

Conclusions: The primary structure suggested that the Aotus protein has a functional role similar to that of humans, and that the initial T-cell activation steps are also similar. However, the great variation observed in CD3epsilon-extracellular region in humans in contrast to the Aotus (especially in areas that are surface-exposed) indicated that some monoclonal antibodies against the human CD3 complex will not recognize these Aotus determinants.