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J Biol Chem. 2016 Nov 11;291(46):24133-24147. Epub 2016 Sep 12.

Molecular Architecture of Contactin-associated Protein-like 2 (CNTNAP2) and Its Interaction with Contactin 2 (CNTN2).

Author information

1
From the Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720.
2
the Center for Mitochondrial Biology and Medicine, Key Laboratory of Biomedical Information Engineering of Ministry of Education, School of Life Science and Technology and Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
3
the Department of Pharmacology and Toxicology.
4
the Sealy Center for Structural Biology and Molecular Biophysics and.
5
the University of Michigan, Ann Arbor, Michigan 48109.
6
the Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, Texas 77555, and.
7
From the Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, gren@lbl.gov.
8
the Department of Pharmacology and Toxicology, garudenk@utmb.edu.

Abstract

Contactin-associated protein-like 2 (CNTNAP2) is a large multidomain neuronal adhesion molecule implicated in a number of neurological disorders, including epilepsy, schizophrenia, autism spectrum disorder, intellectual disability, and language delay. We reveal here by electron microscopy that the architecture of CNTNAP2 is composed of a large, medium, and small lobe that flex with respect to each other. Using epitope labeling and fragments, we assign the F58C, L1, and L2 domains to the large lobe, the FBG and L3 domains to the middle lobe, and the L4 domain to the small lobe of the CNTNAP2 molecular envelope. Our data reveal that CNTNAP2 has a very different architecture compared with neurexin 1α, a fellow member of the neurexin superfamily and a prototype, suggesting that CNTNAP2 uses a different strategy to integrate into the synaptic protein network. We show that the ectodomains of CNTNAP2 and contactin 2 (CNTN2) bind directly and specifically, with low nanomolar affinity. We show further that mutations in CNTNAP2 implicated in autism spectrum disorder are not segregated but are distributed over the whole ectodomain. The molecular shape and dimensions of CNTNAP2 place constraints on how CNTNAP2 integrates in the cleft of axo-glial and neuronal contact sites and how it functions as an organizing and adhesive molecule.

KEYWORDS:

cell adhesion; cell surface receptor; contactin; contactin-associated protein like; neuropsychiatric disorders; protein-protein interaction; single particle analysis; structural biology; synapse; synaptic organizer

PMID:
27621318
PMCID:
PMC5104938
DOI:
10.1074/jbc.M116.748236
[Indexed for MEDLINE]
Free PMC Article

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