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 Brilliant Violet 786
Brilliant™ Violet 786 (BV786) is a far-red-emitting tandem fluorophore that can be excited by the 405 nm Violet laser and collected using a 780/60 bandpass filter. BV750 has an excitation peak at 405 nm and an emission peak at 786 nm. Due to its unique Stokes shift, few dyes have identical or near identical excitation and emission spectrums, but the nearest alternatives are Qdot® 800 and SuperBright 780 (ThermoFisher), and Brilliant™ Violet 785 (BioLegend). What's the difference between BV785 and BV786? BV785 is a BioLegend color, while BV786 is a BD Biosciences color, but they exhibit the same spectral properties. This dye exhibits a medium level of brightness and is most often used in flow cytometry. Older instruments may not be set up for a dye with such a large Stokes shift, however BV786 is especially well suited for spectral cytometers or sorters. This dye is part of the Brilliant™ Violet dye line of fluorescent polymers. Brilliant™ Violet 421 polymer is employed as the donor molecule in a series of tandem dyes with acceptor molecules emitting at various points across the visible light spectrum. The Brilliant™ Violet dyes are a superior alternative to QDot nanocrystals and similar to SuperNova dye from Beckman Coulter and StarBright dyes from Bio-Rad.