About IgM
Immunoglobulins (Ig) are the antigen recognition molecules of B cells. An Ig molecule is made up of 2 identical heavy chains and 2 identical light chains (see MIM 147200) joined by disulfide bonds so that each heavy chain is linked to a light chain and the 2 heavy chains are linked together. Each Ig heavy chain has an N-terminal variable (V) region containing the antigen-binding site and a C-terminal constant (C) region, encoded by an individual C region gene, that determines the isotype of the antibody and provides effector or signaling functions. The heavy chain V region is encoded by 1 each of 3 types of genes: V genes (see MIM 147070), joining (J) genes (see MIM 147010), and diversity (D) genes (see MIM 146910). The C region genes are clustered downstream of the V region genes within the heavy chain locus on chromosome 14. The IGHM gene encodes the C region of the mu heavy chain, which defines the IgM isotype. Naive B cells express the transmembrane forms of IgM and IgD (see IGHD; MIM 1471770) on their surface. During an antibody response, activated B cells can switch to the expression of individual downstream heavy chain C region genes by a process of somatic recombination known as isotype switching. In addition, secreted Ig forms that act as antibodies can be produced by alternative RNA processing of the heavy chain C region sequences. Although the membrane forms of all Ig isotypes are monomeric, secreted IgM forms pentamers, and occasionally hexamers, in plasma (summary by Janeway et al., 2005).[supplied by OMIM, Aug 2010]

About Alexa Fluor 594
Alexa Fluor™ 594 (AF594, Alexa 594) has an excitation peak at 590 nm and an emission peak at 617 nm, and is spectrally similar to Texas Red (ThermoFisher Scientific), DyLight™ 594 (ThermoFisher Scientific), iFluor® 594 (ATT Bioquest) and iFluor® 610 (ATT Bioquest), CF®594 (Biotium), and ATTO 594 (ATTO-TEC). Alexa 594 is commonly used for flow cytometry,fluorescence microscopy and super-resolution microscopy. It is very bright, photostable, and pH insensitive.