Fig. 2.
Immunoblotting NMR brain homogenates using capillary electrophoresis with anti-human tau antibodies indicates high protein sequence homology and a unique NMR-expressed tau protein. (A) Naked mole-rat tau is immunoreactive to many well-characterized anti-tau antibodies. Based on human tau 4R2N sequence, Tau5 recognizes tau amino acids 210-229, a region immediately upstream of the microtubule binding domains; HT7 recognizes tau amino acids 159-163 within the proline rich domain; and Tau46 recognizes the far carboxy-terminal residues 401-441. RD3 and RD4 recognize tau proteins lacking (RD3) or expressing (RD4) microtubule-binding domain 2. Naked mole-rat tau is immunoreactive to all antibodies and appears as a much larger protein with slower electrophoretic mobility than either mouse (Ms) or human (Hu) tau. (B) Artificial immunoblots produced by capillary electrophoresis clearly illustrate that naked mole-rat tau undergoes a progressive shift in molecular weight during development. (C) The capillary electrophoresis electropherograms allow the acute discernment of distinct protein bands, which then generates the artificial blot shown in (B). Electropherograms indicate that neonatal naked mole-rat tau consists of two distinct bands: a prominent 62kDa band and a minor 72kDa band. During the first week of development, 72kDa tau expression increases to levels higher than 62kDa tau. By 3 months of age, 72kDa tau is heavily expressed and the emergence of a higher 88kDa band appears. By 1 year of age the high molecular weight 88kDa tau protein becomes the prominent tau protein with lower levels of 72kDa band remaining. Ms: mouse; HuRc: Recombinant human tau 4R2N; HuTg: transgenic mouse expressing wild type human tau, hTau (Andorfer, et al., 2003); Mo: months; Yr: year. *'s on electropherograms indicate 66, 90, and 116kDa respectively.