Phosphopeptides from proteins involved in regulation of protein degradation that are altered in abundance in response to dDAVP in rat IMCD suspensions* (See below for narrative)
*Peptides satisfied dual criteria: |Mean log2(dDAVP/Control)| > 0.342 and FDR < 0.005. The value 0.342 defines the 95% confidence interval for control:control comparisons.
§, Phosphorylated amino acid indicated by *; #, deamidated asparagine or glutamine; †, False Discovery Rate; ‡ Imported from "FUNCTION" field of UniProt record
| Gene Symbol | UniProt no. | Residue(s) | Peptide§ | Mean log2(dDAVP/Vehicle) | SD log2(dDAVP/Vehicle) | FDR† | Function in regulation of transcription‡ |
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Vasopressin-mediated increase in protein stability. Vasopressin has been shown to increase the half-life (stability) of AQP2 (Sandoval, 2013), (Nedvetsky, 2010)], although the molecular mechanisms are not well understood. The above table lists altered phosphopeptide abundances for proteins involved in regulation of protein degradation and which have plausible roles in the vasopressin-mediated increase in AQP2 half-life. Of possible interest is the ubiquitin E3 ligase substrate adaptor protein Dcaf8, which undergoes a marked increase in phosphorylation at Ser118 at a site compatible with phosphorylation by PKA or another basophilic protein kinase. Usp10 also underwent an increase in phosphorylation at a putative PKA-target site, Ser608. Usp10 is a deubiquitylating enzyme that has been shown to regulate early endosomal recycling of the chloride channel CFTR in airway epithelial cells (Bomberger, 2009) and to be critical to vasopressin-induced trafficking of the epithelial sodium channel (ENaC) to the plasma membrane (Boulkroun, 2008). Inasmuch as trafficking of ENaC and AQP2 to the apical membrane of collecting duct principal cells, it seems very possible that Usp10 regulates AQP2 in the same manner as it regulates ENaC.