Final answer:
The type of immunoglobulin that forms a pentamer is IgM, which is the first antibody to respond to antigens, capable of binding to ten identical antigens due to its pentamer structure.
Step-by-step explanation:
The type of immunoglobulin that forms a pentamer is IgM. IgM is the largest antibody molecule and the first to be produced in response to antigens. It is a pentamer, which means that five IgM monomers are linked together by intermolecular disulfide bonds and a J-chain. This structure allows IgM to bind to ten identical antigens simultaneously.
Among the five classes of antibodies—IgG, IgA, IgM, IgD, and IgE—IgM is distinctive for its pentameric configuration. This configuration permits IgM to be an important component of the body's initial defense mechanism in both primary and secondary immune responses. Moreover, its presence in the bloodstream can serve as a diagnostic marker for ongoing or recent infections.
The type of immunoglobulin that forms a pentamer is IgM. IgM is the first antibody produced and secreted by B cells during the primary and secondary immune responses. The secreted form of IgM assembles into a pentamer with five monomers of IgM bound together by a protein structure called the J chain. This pentameric structure allows IgM to bind to ten identical antigens, making it an important antibody in the body's defenses.