Changes in intracellular distribution and activity of protein phosphatase PP1γ2 and its regulating proteins in spermatozoa lacking AKAP4

Zaohua Huang, Payaningal R. Somanath, Rumela Chakrabarti, Edward M. Eddy, Srinivasan Vijayaraghavan

Research output: Contribution to journalArticlepeer-review

36 Scopus citations


The second messenger cAMP mediates its intracellular effects in spermatozoa through cAMP-dependent kinase (PKA, formally known as PRKACA). The intracellular organization of PKA in spermatozoa is controlled through its association with A-kinase-anchoring proteins (AKAPs). AKAP4 (A kinase [PRKA] anchor protein 4; also called fibrous sheath component 1 or AKAP 82) is sperm specific and the major fibrous sheath protein of the principal piece of the sperm flagellum. Presumably, AKAP4 recruits PKA to the fibrous sheath and facilitates local phosphorylation to regulate flagellar function. It is also proposed to act as a scaffolding protein for signaling proteins and proteins involved in metabolism. Akap4 gene knockout mice are infertile due to the lack of sperm motility. The fibrous sheath is disrupted in spermatozoa from mutant mice. In this article, we used Akap4 gene knockout mice to study the effect of fibrous sheath disruption on the presence, subcellular distribution, and/or activity changes of PKA catalytic and regulatory subunits, sperm flagellum proteins PP1γ2 (protein phosphatase 1, catalytic subunit, gamma isoform, formally known as PPP1CC), GSK-3 (glycogen synthase kinase-3), SP17 (sperm autoantigenic protein 17, formally known as SPA17), and other signaling proteins. There were no changes in the presence and subcellular distribution for PP1γ2, GSK-3, hsp90 (heat shock protein 1, alpha, formally known as HSPCA), sds22 (protein phosphatase 1, regulatory [inhibitor] subunit 7, formally known as PPP1R7), 14-3-3 protein (tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein), and PKB (thymoma viral proto-oncogene, also known as AKT) in mutant mice. However, the subcellular distributions for PKA catalytic subunit and regulatory subunits, PI 3-kinase (phosphatidylinositol 3-kinase), and SP17 were disrupted in mutant mice. Furthermore, there was a significant change in the activity and phosphorylation of PP1γ2 in mutant compared with wild-type spermatozoa. These studies have identified potentially significant new roles for the fibrous sheath in regulating the activity and function of key signaling enzymes.

Original languageEnglish (US)
Pages (from-to)384-392
Number of pages9
JournalBiology of Reproduction
Issue number2
StatePublished - Feb 2005
Externally publishedYes


  • Akap4 gene knockout
  • Epididymis
  • GSK-3
  • Phosphatases
  • PP1γ2
  • SP17
  • Sperm
  • Sperm motility and transport
  • Testis

ASJC Scopus subject areas

  • Reproductive Medicine
  • Cell Biology


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