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. 2012 Mar 21;7(3):e33889. doi: 10.1371/journal.pone.0033889

Figure 2. PIKfyve expression, phosphorylation, and function.

Figure 2

(A) PIKfyve is phosphorylated at Ser318 by SGK3 and at Ser318 by PKB. Purified recombinant GST-tagged wild-type (WT) or S318A mutant (SA) of PIKfyve was subjected to Western blotting. Blots were incubated with rabbit anti-GST antibody (PIKfyve; lower panel), followed by stripping and reprobing with a rabbit anti-PIKfyve antibody specific for phosphoserine 318 (apS318; top panel). (B) RT-PCR demonstrating that PIKfyve is expressed in hippocampus. Lane 1: cDNA from hippocampus, the two primers bind in exons 19 and 20, respectively, and amplify a 315 bp fragment of PIKfyve; lane 2: control reaction to exclude genomic contamination; lane 3: control reaction without reverse transcriptase; lane 4: control reaction without cDNA. (C) The PIKfyve inhibitor YM201636 and SGK inhibitor EMD638683 suppress the upregulating effect of SGK3 on GluA1 currents. GluA1 current amplitudes in oocytes expressing GluA1. Acute injection of purified active SGK3 protein led to an increase in GluA1 currents. The effects of YM201636 and EMD638683 on GluA1 currents were measured in oocytes before and after acute injection of SGK3 protein. Significant change to GluA1 control (p = 0.013) is indicated by *. Numbers of oocytes were n = 7–36.