The 17 kDa band identified by multiple anti-aquaporin 2 antisera in rat kidney medulla is a histone

Inho Jo, Soren Nielsen, H. William Harris

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


The osmotic water permeability of epithelial cells of the inner medullary collecting duct of the kidney is regulated by antidiuretic hormone (ADH). ADH causes the insertion and removal of cytoplasmic vesicles containing the aquaporin (AQP-2) water channel protein which is recognized by multiple rabbit antipeptide antisera raised against amino acid sequences comprising its cytoplasmic carboxyl terminal. Immunoblots of rat kidney membrane fractions as well as human urine have all shown that AQP-2 is expressed exclusively by collecting duct cells and have identified a 29 kDa band (corresponding to the nonglycosylated AQP-2 protein), a broad 35-45 kDa band (corresponding to the mature glycosylated form of AQP-2 protein) and an additional immunoreactive 17 kDa band of unknown origin. We now report that the 17 kDa band identified by these anti-AQP-2 antisera is not an AQP-2 component but rather a denatured histone protein type H2A1. This binding of anti-AQP-2 antisera to denatured H2A1 present in protein samples derived from both kidney inner medulla and human urine is blocked specifically by preincubation of immunoblots with solutions containing the acidic protein gelatin.

Original languageEnglish
Pages (from-to)91-101
Number of pages11
JournalBBA - Biomembranes
Issue number1
StatePublished - 21 Feb 1997

Bibliographical note

Funding Information:
This investigation was supported in part by NIH grants DK38874 and HL39081 (H.W.H.) and the Novo Nordisk Foundation (S.N.).


  • Antidiuretic hormone
  • Aquaporin 2 water channel
  • Histone
  • Kidney
  • Papilla


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