Unusual traits shape the architecture of the Ig ancestor molecule.

ABSTRACT: Understanding the ancestral Ig domain's molecular structure and tracing the evolution of Ig-like proteins are fundamental components missing from our comprehension of their evolutionary trajectory and function. We have determined high-resolution structures of two Ig-like proteins from the evolutionary most ancestral phylum, Porifera. The structures reveal N-terminal Ig-like domains with an unconventional configuration of features that set them apart from canonical Ig domains. These findings prompted us to call this novel domain as Ig "Early Variable" (EV)-set. Remarkably, the EV-sets are linked to C1-set domains. To the best of our knowledge, the C1-set has not been previously reported in non-vertebrates. The IgV and IgC1 tandems and their combination into functional Ig-like receptors are

SUBMITTER: Urdiciain A 

PROVIDER: S-EPMC11926128 | biostudies-literature | 2025 Mar

REPOSITORIES: biostudies-literature