Mixed neuron glia cultures stain with CPCA-int (red) and counterstained with RPCA-Cor1a
, EnCor’s rabbit polyclonal antibody to Coronin 1a, (green) which is an excellent marker of microglia and lymphocytes. The chicken internexin antibody is an excellent marker of neuronal processes in these cultures.
α-internexin is a Class IV intermediate filament originally discovered as it copurifies with other neurofilament subunits (1). On SDS-PAGE gels it runs with an apparent molecular weight of 64 to 66 kDa, with some species variability, although the real molecular weight is about 55 kDa; as with the other neurofilament subunits the presence of highly negatively charged sequences results in reduction of SDS-PAGE mobility. α-internexin is related to but distinct from the better known neurofilament triplet proteins, NF-L, NF-M and NF-H, having similar protein sequence motifs and a similar intron organization. It is expressed only in neurons and in large amounts early in neuronal development, but is down-regulated in many neurons as development proceeds.
Many classes of mature neurons contain α-internexin in addition to NF-L, NF-M and NF-H. In some mature neurons α-internexin is the only neurofilament subunit expressed. Antibodies to α-internexin are therefore unique probes to study and classify neuronal types and follow their processes in sections and in tissue culture. In addition the very early developmental expression of α-internexin means its presence is an early and convenient diagnostic feature of neuronal progenitors cells and other cell committed to the neuronal lineage. In addition recent studies show a marked up-regulation of a-internexin during neuronal regeneration (2). The use of antibodies to this protein in the study of brain tumors has not been examined to date, but is likely to be of interest.
The HGNC name for this protein is INA.
This antibody was generated in chicken by standard procedures using a full length cDNA encoding rat alpha-internexin as described (4). The resulting polyclonal antibody was extracted from egg yolk and belongs to the IgY subclass. This is the chicken homologue of mammalian IgG and can be used in the same general way, with the caveat that this type of antibody does not bind either Protein A or Protein G. Suitable second antibody reagents can be obtained from many vendors including Molecular Probes and Sigma-Aldrich.