Molecular Biology Reports

, Volume 39, Issue 3, pp 3185–3196

The mouse B cell-specific mb-1 gene encodes an immunoreceptor tyrosine-based activation motif (ITAM) protein that may be evolutionarily conserved in diverse species by purifying selection

  • Richard Sims
  • Virginia Oberholzer Vandergon
  • Cindy S. Malone

DOI: 10.1007/s11033-011-1085-7

Cite this article as:
Sims, R., Vandergon, V.O. & Malone, C.S. Mol Biol Rep (2012) 39: 3185. doi:10.1007/s11033-011-1085-7


The B-lymphocyte accessory molecule Ig-alpha (Ig-α) is encoded by the mouse B cell-specific gene (mb-1), and along with the Ig-beta (Ig-β) molecule and a membrane bound immunoglobulin (mIg) makes up the B-cell receptor (BCR). Ig-α and Ig-β form a heterodimer structure that upon antigen binding and receptor clustering primarily initiates and controls BCR intracellular signaling via a phosphorylation cascade, ultimately triggering an effector response. The signaling capacity of Ig-α is contained within its immunoreceptor tyrosine-based activation motif (ITAM), which is also a key component for intracellular signaling initiation in other immune cell-specific receptors. Although numerous studies have been devoted to the mb-1 gene product, Ig-α, and its signaling mechanism, an evolutionary analysis of the mb-1 gene has been lacking until now. In this study, mb-1 coding sequences from 19 species were compared using Bayesian inference. Analysis revealed a gene phylogeny consistent with an expected species divergence pattern, clustering species from the primate order separate from lower mammals and other species. In addition, an overall comparison of non-synonymous and synonymous nucleotide mutational changes suggests that the mb-1 gene has undergone purifying selection throughout its evolution.


Ig-alpha (Ig-α)B cell-specificmb-1B-cell receptor (BCR)Immunoreceptor tyrosine-based activation motif (ITAM)Evolutionary divergenceBioinformatics

Supplementary material

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Supplementary material 1 (DOC 39 kb)
11033_2011_1085_MOESM2_ESM.doc (47 kb)
Supplementary material 2 (DOC 47 kb)
11033_2011_1085_MOESM3_ESM.doc (33 kb)
Supplementary material 3 (DOC 33 kb)

Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  • Richard Sims
    • 1
  • Virginia Oberholzer Vandergon
    • 1
  • Cindy S. Malone
    • 1
  1. 1.Department of BiologyCalifornia State University NorthridgeNorthridgeUSA