Similarities and differences between tau protein and chromobindin A.

Tau protein and Chromobindin A have several features in common but are not identical. Both consist of a small group of closely related proteins which can form aggregates. Both have a similar range of molecular weights (53-62 kDa) and isoelectric points (6.0-7.5). While Chromobindin A is known to be membrane associated, there is evidence that Tau protein also interacts with phospholipids. Both, not present in all tissues, can be found in the adrenal medulla. Despite these similarities both classes of proteins are unique and immunologically distinct. A rabbit antisera to Tau does not cross react with Chromobindin A. In addition, while protein kinase C and Ca/Calmodulin-dependent protein kinase II phosphorylate Tau protein, they do not phosphorylate Chromobindin A, demonstrating the specificity of these kinases for Tau protein phosphorylation.