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figure 4

Figure 4 - Synthesis of a mu immunoglobulin heavy chain

(a1) At the DNA level, in a first step, one of the IGHD genes is joined to one of the IGHJ genes, with deletion of the intermediary DNA, to create a partially rearranged D-J gene. In a second step (a2), one of the IGHV gene is joined to D-J, with deletion of the intermediary DNA, to generate a completely rearranged IGHV-D-J gene. (b) The rearranged IGHV-D-J gene is transcribed with the IGHM gene into a IGHV-D-J-M (or IGHV-D-J-Cmu) premessenger RNA. (c) The RNA sequences corresponding to the introns and to the non-used IGHJ genes are excised by splicing, and a mature messenger which comprises the spliced coding regions, and the 5' and 3' untranslated sequences, is obtained. (d) The messenger RNA is translated into a polypeptide chain by the ribosomes. (e) The signal peptide is cleaved off by a peptidase following the entry of the polypeptide chain in the endoplasmic reticulum, and a mature mu heavy chain is produced.

L=L-PART1 (L: for Leader).