Discussions

The B cell's endoplasmic reticulum (ER) is where IgM polymerization starts. Two heavy chains and two light chains connected by disulfide bonds make up each IgM monomer. An additional domain called Mu is present in the heavy chains and is important to the polymerization process. The Mu domain's C-terminal cysteine residues are essential to the polymerization process. Pentamers or hexamers can be formed when these residues combine with residues in other monomeric units to generate disulfide bonds. The invariant region's cysteine residues C414, C575, and C414 are crucial to this process, according to experimental data. The J-chain is a new peptide chain that is added after the pentameric or hexameric structure first forms.