PT  - JOURNAL ARTICLE
AU  - Gauthier, Laurent
AU  - Lemmers, Bénédicte
AU  - Guelpa-Fonlupt, Valérie
AU  - Fougereau, Michel
AU  - Schiff, Claudine
TI  - μ-Surrogate Light Chain Physicochemical Interactions of the Human PreB Cell Receptor: Implications for V<sub>H</sub> Repertoire Selection and Cell Signaling at the PreB Cell Stage
DP  - 1999 Jan 01
TA  - The Journal of Immunology
PG  - 41--50
VI  - 162
IP  - 1
4099  - http://www.jimmunol.org/content/162/1/41.short
4100  - http://www.jimmunol.org/content/162/1/41.full
SO  - J. Immunol.1999 Jan 01; 162
AB  - The surrogate light chain (SL) composed of the λ-like and VpreB polypeptides is organized as two Ig domains and an extra-loop structure. It associates to the μ-chain in preB cells. We have produced human VpreB, SL, two Fdμ (VH-CH1), and the two corresponding Fab-like (Fdμ-SL) recombinant proteins in baculovirus. The correctness of the general conformation of the proteins was assessed by epitope mapping and affinity measurements using a new batch of anti-VpreB mAbs. Plasmon resonance analysis showed that both VpreB and the entire SL associated with the Fdμ fragments, with Kd values of 3 × 10−8 M for VpreB-Fdμ and of 10−9 to 10−10 M, depending upon the VH, for SL-Fdμ. These results indicate that the λ-like chain, in addition to be covalently bound to the Cμ1 domain, also interacts with the VH domain. Therefore, a dual role of the SL emerges: 1) interaction of the C-domain of λ-like would release the μ-chain from its interaction with binding protein in the endoplasmic reticulum, and 2) interaction of a part of λ-like and most of VpreB would bind to VH, ensuring a “quality control” of the native heavy chain that represents the first step of selection of the B cell repertoire. We also demonstrated that two Fab-like fragments did not interact with each other, suggesting that activation of the cell surface preB receptor does not involve aggregation neither in cis nor in trans of the Fab-like structures.