| 1999 |
AKAP3 (AKAP110) is a sperm-specific A-kinase anchoring protein whose RII-binding domain was mapped using truncated mutants; the domain forms an amphipathic helix with eight conserved positions responsible for RII interaction. AKAP3 localizes to the acrosomal region of the sperm head and along the entire principal piece, co-compartmentalizing with both RI and RII regulatory subunits of PKA. |
Truncated mutant binding assays, immunocytochemistry, Northern blot, in situ hybridization |
Molecular Endocrinology |
High |
10319321
|
| 1999 |
AKAP3 (FSP95/SOB1) is localized to the ribs of the fibrous sheath in the principal piece of the human sperm tail, as determined by indirect immunofluorescence and immunoelectron microscopy. AKAP3 undergoes tyrosine phosphorylation during capacitation of human spermatozoa. |
Immunoelectron microscopy, indirect immunofluorescence, Western blot |
Biology of Reproduction |
High |
10529264
|
| 2001 |
Activated Gα13 (heterotrimeric G protein α subunit) directly interacts with AKAP3 (AKAP110), forming a complex with both the regulatory (rPKA) and catalytic (cPKA) subunits of PKA. Gα13 binding to AKAP3 releases the catalytic subunit of PKA from the AKAP3-rPKA complex, resulting in cAMP-independent PKA activation; AKAP110 potentiates this Gα13-induced PKA activation. |
Yeast two-hybrid screening, in vitro binding assay, co-immunoprecipitation, PKA activity assay |
Current Biology |
High |
11696326
|
| 2004 |
Bicarbonate stimulates tyrosine phosphorylation of AKAP3 in human spermatozoa through activation of soluble adenylate cyclase (sAC), leading to increased cAMP production and enhanced recruitment of PKA to AKAP3, and this signaling cascade increases sperm motility and hyperactivation. |
Western blot, pharmacological inhibition (sAC inhibitor 2OH-estradiol, DIDS, LY294002), sperm motility analysis |
Biology of Reproduction |
Medium |
15342355
|
| 2005 |
AKAP3 selectively binds PDE4A5 (but not PDE4D) isoform in bovine spermatozoa, as demonstrated by co-immunoprecipitation in COS cells co-transfected with AKAP3 and PDE isoforms, and confirmed by pulldown from sperm lysates. AKAP3 functions as a scaffolding protein that co-localizes with PDE4A in the principal piece to regulate local cAMP concentrations. |
Co-immunoprecipitation (COS cell co-transfection), pulldown assay from sperm lysates, immunolocalization |
Biology of Reproduction |
High |
16177223
|
| 2011 |
AKAP3 forms a complex with CABYR (calcium-binding tyrosine phosphorylation-regulated protein) and Ropporin in the human sperm fibrous sheath. CABYR binds AKAP3 via its RII-like domain, as confirmed by co-immunoprecipitation and yeast two-hybrid assays. |
Co-immunoprecipitation, mass spectrometry, Western blot, yeast two-hybrid |
Asian Journal of Andrology |
High |
21240291
|
| 2013 |
AKAP3 is degraded via the proteasomal machinery during bovine sperm capacitation (inhibited by MG-132). Binding of PKARII to AKAP3 protects AKAP3 from degradation; disruption of PKARII anchoring (with Ht31 peptide) or inhibition/activation of PKA both increase AKAP3 degradation rate. Intracellular alkalization (NH4Cl) also enhances AKAP3 degradation. |
Western blot, proteasome inhibitor (MG-132), Ht31 peptide disruption, PKA activity modulators (H89, 8Br-cAMP), calcium chelation |
PLoS ONE |
Medium |
23894359
|
| 2014 |
AKAP3 synthesis during mouse spermiogenesis is regulated by PKA signaling and RNA-binding proteins (RBPs) PIWIL1, PABPC1, and NONO. Nascent AKAP3 forms a protein complex with PKA and these RBPs, which co-localize at the chromatoid body. Activation of PKA positively regulates AKAP3 protein synthesis without changing mRNA levels in elongating spermatids. |
Co-immunoprecipitation, protein mass spectrometry, RNA EMSA, sucrose gradient sedimentation, immunofluorescence, PKA activator treatment |
Biology of Reproduction |
Medium |
24648398
|
| 2014 |
AKAP3 is a dual-specificity anchoring protein that interacts with both RIα and RIIα regulatory subunits of PKA via two conserved N-terminal amphipathic peptide domains (named 'dual' and 'RI' domains). In elongating spermatids AKAP3 interacts preferentially with RIα, while in mature sperm it co-localizes exclusively with RIIα in the principal piece. |
Mutagenesis of amphipathic domains, in vivo and in vitro binding assays, immunofluorescence, co-immunoprecipitation |
Molecular Reproduction and Development |
High |
24687590
|
| 2015 |
AKAP3 undergoes tyrosine dephosphorylation during sperm capacitation, and its degradation rate is regulated by its tyrosine phosphorylation status: inhibition of tyrosine phosphatase reduces AKAP3 degradation, while inhibition of tyrosine kinase enhances it. Blocking AKAP3 degradation with anti-AKAP3 antibody in permeabilized cells inhibits the acrosome reaction, demonstrating that AKAP3 degradation is required for capacitation. |
Immunoprecipitation, Western blot, tyrosine kinase/phosphatase inhibitors, anti-AKAP3 antibody microinjection into permeabilized cells, FITC-PSA acrosome reaction assay |
Biochimica et Biophysica Acta |
Medium |
26093290
|
| 2019 |
Recombinant human oviduct-specific glycoprotein (rHuOVGP1) enhances tyrosine phosphorylation of AKAP3 in the fibrous sheath during capacitation, as shown by co-migration of the pY 105 kDa band with AKAP3 on Western blot and confirmed by immunoprecipitation and co-localization by immunofluorescence. |
Western blot, immunoprecipitation, confocal immunofluorescence |
Journal of Assisted Reproduction and Genetics |
Medium |
31254143
|
| 2020 |
Genetic ablation of AKAP3 in mice causes male sterility due to defects in fibrous sheath formation, loss of sperm motility, and global proteome changes in sperm including mislocalization of PKA subunits and accumulation of RNA metabolism/translation factors. Sperm from both Akap3 and Akap4 null mice accumulate F-actin filaments during post-testicular epididymal maturation. |
Mouse knockout (Akap3 null), proteomics, immunofluorescence, electron microscopy, sperm motility analysis |
Development |
High |
31969357
|
| 2022 |
AKAP3 is degraded by the ubiquitin-26S proteasome pathway during sperm capacitation; inhibition of the 26S proteasome with MG132 causes accumulation of ubiquitinated AKAP3 and uncoupling of PKA from AKAP3, leading to PKA degradation by UPP, reduced tyrosine phosphorylation, and increased serine/threonine phosphorylation. |
Co-precipitation assays, Western blot, proteasome inhibitor (MG132), flow cytometry |
Animal Reproduction Science |
Medium |
36209601
|
| 2023 |
STK33 kinase directly phosphorylates AKAP3 (and AKAP4); differential phosphoproteomic analysis and in vitro kinase assay identified AKAP3 as a novel phosphorylation substrate of STK33. Loss of STK33 reduces AKAP3 expression in testis and disrupts fibrous sheath assembly in sperm. |
Differential phosphoproteomics, in vitro kinase assay, Stk33 knockout/knock-in mice, Western blot, electron microscopy |
Molecular & Cellular Proteomics |
High |
37146716
|
| 2024 |
The dual and RI amphipathic domains in the N-terminus of AKAP3, responsible for binding RIα and RIIα of PKA, are required for sperm hyperactivation and male fertility. Deletion of these domains in mice causes RIα mislocalization from the principal piece to the midpiece of the sperm tail, reduces PKA substrate phosphorylation, and abolishes hyperactivation under capacitation conditions, without altering PKA subunit protein levels. AKAP3 shows a preference for binding RIα over RIIα. |
Domain deletion mutant mice, protein-protein interaction assays, immunofluorescence, sperm motility/hyperactivation analysis, Western blot for phosphorylation |
Biology of Reproduction |
High |
38145487
|