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5.4 BCR & the Immunoglobulin Superfamily β Test 1
Q1. The B-cell receptor (BCR) complex consists of:β Membrane immunoglobulin plus IgΞ±/IgΞ² (CD79a/CD79b)
Q2. Signal transduction by the BCR is carried out by:β IgΞ± and IgΞ² (CD79a/CD79b) via their ITAMs
Q3. The immunoglobulin superfamily is defined by members that share:β The immunoglobulin domain (a conserved fold)
Q4. Which of the following is a member of the immunoglobulin superfamily?β The T-cell receptor
Q5. Membrane and secreted forms of immunoglobulin from the same B cell are generated by:β Alternative processing of the heavy-chain mRNA
Q6. The CD19/CD21 co-receptor complex on B cells functions to:β Lower the threshold for BCR activation when antigen is complement-tagged
Q7. The variable domains of an immunoglobulin are an example of an Ig domain that is:β A V-set immunoglobulin domain
Q8. ITAMs (immunoreceptor tyrosine-based activation motifs) function to:β Recruit kinases that propagate activating signals when phosphorylated
Q9. On a naive mature B cell, the membrane immunoglobulin isotypes expressed are:β IgM and IgD
Q10. MHC class I and class II molecules are members of the immunoglobulin superfamily because they:β Contain immunoglobulin-like domains
Q11. Antigen binding to the BCR can lead to internalisation so that the B cell can:β Process and present antigen on MHC II to helper T cells
Q12. Adhesion molecules such as ICAM-1 and VCAM-1 belong to the:β Immunoglobulin superfamily
Q13. The hinge-like flexibility and domain organisation of antibodies reflect their being built from:β Repeated immunoglobulin domains
Q14. Cross-linking of multiple BCRs by a multivalent antigen is important because it:β Clusters receptors to trigger effective signalling
Q15. CD4 and CD8 co-receptors are immunoglobulin-superfamily molecules that:β Bind conserved regions of MHC II and MHC I respectively
Q16. The B-cell co-receptor links innate immunity to adaptive responses by sensing:β Complement (C3d) deposited on antigen
Q17. The cytoplasmic tail of membrane immunoglobulin is short, which means the BCR:β Depends on associated IgΞ±/IgΞ² for signalling
Q18. An advantage of the modular immunoglobulin domain in evolution is that it:β Can be reused in many recognition and adhesion molecules
Q19. Signalling through the BCR ultimately leads to:β B-cell activation and changes in gene expression
Q20. The primary (membrane) B-cell receptor on a mature naive B cell is:β Membrane IgD (with IgM)
Q21. Transmembrane immunoglobulin molecules disulphide-linked together on a B cell form the:β B-cell receptor (BCR)
Q22. The B-cell co-receptor complex consists of:β CD19, CD21 (CR2) and CD81 (TAPA-1) together
Q23. Match each molecule with its description and select the correct option.β A-iii, B-iv, C-i, D-ii