3KG5

Crystal structure of human Ig-beta homodimer

Summary for 3KG5

• Entry DOI: 10.2210/pdb3kg5/pdb
• Descriptor: B-cell antigen receptor complex-associated protein beta chain (2 entities in total)
• Functional Keywords: cd79b, ig-beta, bcr, immunoglobulin domain, protein binding
• Biological source: Homo sapiens (human)
• Cellular location: Cell membrane; Single-pass type I membrane protein: P40259
• Total number of polymer chains: 2
• Total formula weight: 30999.10

Authors

Radaev, S.,Sun, P.D. (deposition date: 2009-10-28, release date: 2010-08-25, Last modification date: 2024-10-16)

Primary citation

Radaev, S.,Zou, Z.,Tolar, P.,Nguyen, K.,Nguyen, A.,Krueger, P.D.,Stutzman, N.,Pierce, S.,Sun, P.D.
Structural and Functional Studies of Igalphabeta and Its Assembly with the B Cell Antigen Receptor.
Structure, 18:934-943, 2010

PubMed Abstract: The B cell antigen receptor (BCR) plays an essential role in all phases of B cell development. Here we show that the extracellular domains of murine and human Igbeta form an I-set immunoglobulin-like structure with an interchain disulfide between cysteines on their G strands. Structural and sequence analysis suggests that Igalpha displays a similar fold as Igbeta. An Igalphabeta heterodimer model was generated based on the unique disulfide-bonded Igbeta dimer. Solution binding studies showed that the extracellular domains of Igalphabeta preferentially recognize the constant region of BCR with mu chain specificity, suggesting a role for Igalphabeta to enhance BCRmu chain signaling. Cluster mutations on Igalpha, Igbeta, and a membrane-bound form of immunoglobulin (mIgM) based on the structural model identified distinct areas of potential contacts involving charged residues on both subunits of the coreceptor and the Cmu4 domain of mIgM. These studies provide the first structural model for understanding BCR function.

PubMed: 20696394
DOI: 10.1016/j.str.2010.04.019

Experimental method

X-RAY DIFFRACTION (3.2 Å)