TABLE I.

Assessment of Dephosphorylation of Hyperphosphorylated Tau by Ser/Thr PPases

Site					Site
Y18					S235
T39					S237
S46					S238
S68					S241
T69					S258
T71					S262	PP1	PP2A+++	PP2B +++²,³	PP5
S113					S285
T123					S289
S137					S305
T153					S324
T175					S352
T181	PP1	PP2A	PP2B¹		S356		PP2A
S184					Y294
S185					S396	PP1	PP2A^*	PP2B +++²,³	PP5
S191					S400
Y197					T403		PP2A
S198			PP2B²,³		S404	PP1	PP2A	PP2B²,³	PP5
S199	PP1	PP2A	PP2B²,³	PP5	S409	PP1+++	PP2A+++	PP2B+++	PP5+++
S202	PP1	PP2A	PP2B²,³	PP5	S412
T205	PP1+++	PP2A+++^*	PP2B	PP5+++	S413
S208					T414
S210					S416
T212	PP1+++	PP2A+++^*	PP2B	PP5+++	S422	PP1	PP2A	PP2B
S214	PP1+++	PP2A	PP2B	PP5	T427
T217	PP1	PP2A^*	PP2B		S433
T231		PP2A	PP2B¹		S435

More than 50 sites of phosphorylation have been identified in tau.²⁶ The dephosphorylation of a limited number has been analyzed using available phospho-specific antibodies, and in in vitro assays various preparations of PP1,^28,29 PP2A,^28,30,31 PP2B,^28,32 and PP5^28,33,44 exhibit selectivity for different sites (+++ indicates highest activity in in vitro assays).

Note that studies of PP2A came to a different assessment of the dephosphorylation of some sites. Studies of the role of PP2B were also assessed in vivo;

PP2B knockdown in rat brain³⁵

cyclosporin infusion into mouse left lateral ventricle³⁶

FK506 infusion in mouse³⁷