Faculty Opinions recommendation of Complementary chimeric isoforms reveal Dscam1 binding specificity in vivo.

Id-460+ immunoglobulins can be induced in vivo by immunization with dinitrophenyl (DNP) or P. pneumotropica and form two nonoverlapping groups of antibodies with respect to antigen binding specificity. In this study, using Id-460+ antibodies of differing antigen binding specificities, we compared on the molecular genetic level the five gene segment combinations (VH, DH, JH, VL, and JL) that encode the variable regions of these idiotype-positive immunoglobulins. The Id-460 determinant appears to be a conformational or combinatorial determinant encoded by VH460 and VK1 crosshybridizing genes. DH, JH, and JK gene segments appear to have no measurable effect upon expression of Id-460. Finally, antigen binding specificity does not appear to simply localize to any particular gene segment but may in part be the result of somatic mutation and/or VDJH junctional sequences, whose length correlates roughly with antigen binding specificity.

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The role of Fc–FcγR interactions in IgG-mediated microbial neutralization

Journal of Experimental Medicine ◽

10.1084/jem.20151267 ◽

2015 ◽

Vol 212 (9) ◽

pp. 1361-1369 ◽

Cited By ~ 92

Author(s):

Stylianos Bournazos ◽

David J. DiLillo ◽

Jeffrey V. Ravetch

Keyword(s):

Crucial Role ◽

Binding Specificity ◽

Effector Cells ◽

Effector Functions ◽

Bifunctional Molecules

Antibodies are bifunctional molecules, containing a variable Fab domain that mediates binding specificity and a constant Fc domain that bridges antibody-coated targets with FcγR-expressing cells that mediate effector functions. Although traditional mechanisms of antibody-mediated neutralization of microbes have been largely thought to result from Fab–antigen interactions, recent studies suggest that recruitment of FcγR-expressing effector cells by antibodies is a major in vivo mechanism of antibody-mediated protection from infection. In this article, we review FcγR biology, compare mammalian FcγR families, and summarize recent evidence demonstrating the crucial role that Fc–FcγR interactions play during in vivo protection from infection.

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The role of BH3-only protein Bim extends beyond inhibiting Bcl-2–like prosurvival proteins

The Journal of Cell Biology ◽

10.1083/jcb.200905153 ◽

2009 ◽

Vol 186 (3) ◽

pp. 355-362 ◽

Cited By ~ 131

Author(s):

Delphine Mérino ◽

Maybelline Giam ◽

Peter D. Hughes ◽

Owen M. Siggs ◽

Klaus Heger ◽

...

Keyword(s):

Family Members ◽

Binding Specificity ◽

In Vitro Studies ◽

Genetic Approach ◽

Activation Model ◽

Bh3 Domain ◽

Indirect Activation

Proteins of the Bcl-2 family are critical regulators of apoptosis, but how its BH3-only members activate the essential effectors Bax and Bak remains controversial. The indirect activation model suggests that they simply must neutralize all of the prosurvival Bcl-2 family members, whereas the direct activation model proposes that Bim and Bid must activate Bax and Bak directly. As numerous in vitro studies have not resolved this issue, we have investigated Bim's activity in vivo by a genetic approach. Because the BH3 domain determines binding specificity for Bcl-2 relatives, we generated mice having the Bim BH3 domain replaced by that of Bad, Noxa, or Puma. The mutants bound the expected subsets of prosurvival relatives but lost interaction with Bax. Analysis of the mice showed that Bim's proapoptotic activity is not solely caused by its ability to engage its prosurvival relatives or solely to its binding to Bax. Thus, initiation of apoptosis in vivo appears to require features of both models.

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A Conserved Residue in the Yeast Bem1p SH3 Domain Maintains the High Level of Binding Specificity Required for Function

Journal of Biological Chemistry ◽

10.1074/jbc.m111.229294 ◽

2011 ◽

Vol 286 (22) ◽

pp. 19470-19477 ◽

Cited By ~ 9

Author(s):

Maryna Gorelik ◽

Karen Stanger ◽

Alan R. Davidson

Keyword(s):

Sequence Similarity ◽

Consensus Sequence ◽

Binding Specificity ◽

Biologically Relevant ◽

Protein Protein Interaction ◽

Nonspecific Interactions ◽

High Level ◽

Conserved Residue

The yeast Bem1p SH3b and Nbp2p SH3 domains are unusual because they bind to peptides containing the same consensus sequence, yet they perform different functions and display low sequence similarity. In this work, by analyzing the interactions of these domains with six biologically relevant peptides containing the consensus sequence, they are shown to possess finely tuned and distinct binding specificities. We also identify a residue in the Bem1p SH3b domain that inhibits binding, yet is highly conserved for the purpose of preventing nonspecific interactions. Substitution of this residue results in a marked reduction of in vivo function that is caused by titration of the domain away from its proper targets through nonspecific interactions with other proteins. This work provides a clear illustration of the importance of intrinsic binding specificity for the function of protein-protein interaction modules, and the key role of “negative” interactions in determining the specificity of a domain.

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