First a review… Adopt as a perspective that: One B-cell produces one antibody Make that perspective more exacting: One B-cell produces one idiotype. Cassettes (V, J, [D],) (aka gene segments) “fuse” (to make an idiotype). Fusing occurs because RAG recognizes one turn/two turn signals on cassettes. CDR3 develops through junctional flexibility (trimming) and addition of P & N nucleotides (expanding). CDR1 and CDR2 (especially) and CDR3 become more varied because of somatic hypermutation.

First a review… now with images And, I will use images from a different source. Remember to be critical of what “interpretative” drawings convey…

First a review… now with images

First a review… still with images RAG: what does it do? …how does it work?

First a review… still with more images RAG: what does it do? …how does it work? …what about P&N nucleotides?

PART IV (some new stuff) How do immunoglobulins assemble? Some immunoglobulins are in the surface membrane of immature B-cells while other immunoglobulins of the same idiotype are secreted by mature B-cells. What’s the difference? Similarly, identical variable regions can be shared among different isotypes. How? B-cells are diploids with two sets of genetic instructions. How does just one set get expressed?

How do immunoglobulins assemble?

Some immunoglobulins are in the surface membrane of immature B-cells while other immunoglobulins of the same idiotype are secreted by mature B-cells. What’s the difference?

Similarly, identical variable regions can be shared among different isotypes. How?

B-cells are diploids with two sets of genetic instructions B-cells are diploids with two sets of genetic instructions. How does just one set get expressed?

The general scheme of B-cell development STEM CELL  pro (genitor) Bcell pre Bcell Ag-selected ( stimulated)- Bcell Ab secreting plasma cell