3QNZ

Orthorhombic form of IgG1 Fab fragment (in complex with antigenic tubulin peptide) sharing same Fv as IgA

Summary for 3QNZ

• Entry DOI: 10.2210/pdb3qnz/pdb
• Related: 3M8O 3QNX 3QNY 3QO0 3QO1
• Descriptor: Fab fragment of IMMUNOGLOBULIN G1 LIGHT CHAIN, Fab fragment of IMMUNOGLOBULIN G1 HEAVY CHAIN, peptide from Tubulin beta chain, ... (5 entities in total)
• Functional Keywords: immunoglobulin fold, immune system
• Biological source: Homo sapiens (human); More
• Cellular location: Cytoplasm, cytoskeleton: P07437
• Total number of polymer chains: 3
• Total formula weight: 48456.92

Authors

Trajtenberg, F.,Correa, A.,Buschiazzo, A. (deposition date: 2011-02-09, release date: 2012-02-15, Last modification date: 2023-11-01)

Primary citation

Correa, A.,Trajtenberg, F.,Obal, G.,Pritsch, O.,Dighiero, G.,Oppezzo, P.,Buschiazzo, A.
Structure of a human IgA1 Fab fragment at 1.55 angstrom resolution: potential effect of the constant domains on antigen-affinity modulation
Acta Crystallogr.,Sect.D, 69:388-397, 2013

PubMed Abstract: Despite being the most abundant class of immunoglobulins in humans and playing central roles in the adaptive immune response, high-resolution structural data are still lacking for the antigen-binding region of human isotype A antibodies (IgAs). The crystal structures of a human Fab fragment of IgA1 in three different crystal forms are now reported. The three-dimensional organization is similar to those of other Fab classes, but FabA1 seems to be more rigid, being constrained by a hydrophobic core in the interface between the variable and constant domains of the heavy chain (VH-CH1) as well as by a disulfide bridge that connects the light and heavy chains, influencing the relative heavy/light-chain orientation. The crystal structure of the same antibody but with a G-isotype CH1 which is reported to display different antigen affinity has also been solved. The differential structural features reveal plausible mechanisms for constant/variable-domain long-distance effects whereby antibody class switching could alter antigen affinity.

PubMed: 23519414
DOI: 10.1107/S0907444912048664

Experimental method

X-RAY DIFFRACTION (2.2 Å)