Affinage

PDCL

Phosducin-like protein · UniProt Q13371

Length
301 aa
Mass
34.3 kDa
Annotated
2026-06-10
17 papers in source corpus 6 papers cited in narrative 6 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 5/6 claims corpus-supported (83%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

PDCL (phosducin-like protein, PhLP) is a cytosolic regulator of heterotrimeric G-protein signaling that operates through two distinct splice-variant mechanisms (PMID:15745879, PMID:11111839). The long isoform (PhLP1) directly sequesters Gβγ subunits, inhibiting the Gα–Gβγ interaction with high affinity (IC50 ~6 nM) at tissue concentrations sufficient to modulate G-protein function in vivo (PMID:11111839). The short isoform (PhLP-S) instead acts upstream of Gβγ assembly, interfering with Gβγ folding through interaction with the CCT chaperonin subunit TCP-1α; loss of this folding activity drives proteasomal degradation of both Gβ and Gγ (PMID:15745879). PhLP itself associates with the 26S proteasomal subunit SUG1 and is targeted for proteasomal turnover (PMID:9551090). A germ-cell-specific family member supports a conserved role in germ cell maturation, complementing the yeast plp2Δ defect (PMID:12424248), and PhLP-family proteins are required for spermiogenesis and actin cone formation during sperm development [PMID:bio_10.1101_2024.06.24.600488]. The PhLP-3 subfamily additionally carries a conserved thioredoxin-domain cysteine conferring redox activity capable of reducing peroxides in vitro (PMID:30596727). How the G-protein regulatory, chaperonin-linked, and redox activities are integrated within a single cellular program has not been resolved in the available corpus.

Mechanistic history

Synthesis pass · year-by-year structured walk · 6 steps
  1. 1998 Medium

    Established the first physical partner of PhLP and a route for its own regulation, linking PhLP to the proteasome.

    Evidence Yeast two-hybrid, in vitro binding, and Co-IP with the proteasomal subunit SUG1, plus lactacystin-induced accumulation of ubiquitin-reactive PhLP-precipitable protein

    PMID:9551090

    Open questions at the time
    • Does not define the ubiquitin ligase or degron involved
    • Functional consequence of PhLP degradation for G-protein signaling untested
  2. 2000 Medium

    Quantified the long isoform as a direct, high-affinity Gβγ sequestering agent, establishing a phosducin-like inhibitory activity at physiologically relevant concentrations.

    Evidence In vitro pertussis toxin ADP-ribosylation assay comparing recombinant PhLP1 (~6 nM IC50) and PhLP-S (~90 nM), with tissue concentration estimates

    PMID:11111839

    Open questions at the time
    • In vitro single-method assay without cellular validation
    • Does not address isoform-specific regulation in vivo
  3. 2002 Medium

    Demonstrated functional conservation of a PhLP-family germ cell role from yeast to mammals, extending PhLP biology beyond G-protein signaling into spermatogenesis.

    Evidence Yeast plp2Δ complementation by germ-line MgcPhLP, with in situ hybridization and Western blot on spermatogenic fractions

    PMID:12424248

    Open questions at the time
    • Molecular substrate of the germ-cell function not identified
    • Relationship to canonical Gβγ/chaperonin activities unresolved
  4. 2005 High

    Resolved the mechanism of the short isoform, showing it inhibits Gβγ not by binding but by disrupting CCT-chaperonin-mediated Gβγ folding, coupling PhLP to protein quality control.

    Evidence Co-IP, siRNA knockdown epistasis with TCP-1α, and lactacystin rescue in HEK cells

    PMID:15745879

    Open questions at the time
    • Structural basis of the PhLP-S/TCP-1α/Gβγ ternary interaction not defined
    • Switch between folding-chaperone and Gβγ-inhibitory roles unexplained
  5. 2018 Medium

    Identified an enzymatic redox activity in the PhLP-3 subfamily and pinpointed the catalytic residue, distinguishing this branch as a thioredoxin-domain oxidoreductase.

    Evidence Recombinant human PhLP-3 thioredoxin-coupled and TBHP reduction assays, cysteine site-directed mutagenesis, and lethal knockout of the P. berghei orthologue

    PMID:30596727

    Open questions at the time
    • Physiological redox substrate in metazoans unknown
    • Single-lab orthologue-based characterization
  6. 2024 Medium

    Tied PhLP-3 redox activity to a defined developmental requirement, showing it is needed for actin cone formation and spermiogenesis with genetic rescue.

    Evidence Recombinant enzymatic assay plus P-element insertion/excision genetics and testes morphology in Drosophila (preprint)

    PMID:bio_10.1101_2024.06.24.600488

    Open questions at the time
    • Preprint, not yet peer-reviewed
    • Mechanistic link between redox activity and actin cone assembly undefined

Open questions

Synthesis pass · forward-looking unresolved questions
  • It remains unknown how PhLP's distinct activities — direct Gβγ sequestration, CCT-dependent Gβγ folding, proteasomal turnover, and PhLP-3 redox catalysis — are coordinated within a single cellular or developmental program.
  • No unifying structural or pathway model across isoforms and subfamilies
  • Endogenous redox substrate unidentified
  • In vivo regulation of isoform switching uncharacterized

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0098772 molecular function regulator activity 2 GO:0016491 oxidoreductase activity 1 GO:0044183 protein folding chaperone 1
Localization
GO:0005829 cytosol 2
Pathway
R-HSA-162582 Signal Transduction 2 R-HSA-392499 Metabolism of proteins 2
Partners
GNB1GNG2SUG1TCP1

Evidence

Reading pass · 6 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2005 PhLP short splice variant (PhLP-S) inhibits Gβγ signaling not by direct Gβγ binding but by interfering with Gβγ folding via interaction with the CCT chaperonin subunit TCP-1α; knockdown of TCP-1α phenocopied PhLP-S overexpression, causing Gbeta and Ggamma protein down-regulation via proteasomal degradation. Co-immunoprecipitation, siRNA knockdown, lactacystatin proteasome inhibition, stabilization-rescue experiments in HEK cells The Journal of biological chemistry High 15745879
1998 PhLP (phosducin-like protein) interacts with SUG1, a subunit of the 26S proteasome; this interaction was demonstrated by yeast two-hybrid, in vitro binding assay, and co-immunoprecipitation. Inhibition of proteasome function by lactacystin led to accumulation of high-molecular-weight, ubiquitin-immunoreactive protein precipitated by PhLP antiserum, suggesting PhLP/SUG1 interaction targets PhLP for proteasomal degradation. Yeast two-hybrid, in vitro binding assay, co-immunoprecipitation, lactacystin proteasome inhibition Biochimica et biophysica acta Medium 9551090
2000 Recombinant PhLP1 (long splice variant) inhibits the interaction between G-protein alpha and Gβγ subunits with an IC50 of ~6 nM (comparable to phosducin), as measured by Gβγ-dependent ADP-ribosylation of Gαi1 by pertussis toxin; PhLP-S inhibited with IC50 ~90 nM. Tissue concentrations of PhLP1 (~150–200 nM) are sufficient to affect G-protein function in vivo. In vitro pertussis toxin ADP-ribosylation assay, Western blot quantification Naunyn-Schmiedeberg's archives of pharmacology Medium 11111839
2002 A germ-line-specific PhLP family member (MgcPhLP) expressed in pachytene spermatocytes and round spermatids complements the defect of a yeast plp2Δ mutant, demonstrating functional conservation of a meiotic/germ cell maturation role for PhLP-family proteins from yeast to mammals. Yeast complementation assay (plp2Δ rescue), in situ hybridization, Western blot on purified spermatogenic cell fractions The Journal of biological chemistry Medium 12424248
2018 Recombinant human PhLP-3 exhibits redox activity in a thioredoxin-coupled assay and can reduce tert-butyl hydroperoxide in vitro; site-directed mutagenesis identified a conserved cysteine in the thioredoxin domain as the redox-active residue. Knockout of the Plasmodium berghei orthologue (pbphlp-3) was lethal, indicating essentiality. Recombinant protein expression, thioredoxin-coupled redox assay, TBHP reduction assay, site-directed mutagenesis, structural modeling, knockout attempt in P. berghei PloS one Medium 30596727
2024 Drosophila PhLP3 (CG4511) is enzymatically redox-active as a recombinant protein with kinetics similar to characterized orthologues; P-element insertion causing PhLP3 downregulation renders male flies sterile with impaired spermiogenesis and absence of actin cones during sperm maturation; P-element excision restores fertility, demonstrating a direct requirement for PhLP3 in actin cone formation and sperm development. Recombinant protein expression and enzymatic assay, P-element insertion/excision genetics, microscopic analysis of testes morphology bioRxivpreprint Medium bio_10.1101_2024.06.24.600488

Source papers

Stage 0 corpus · 17 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2005 Activation of H-H, C-H, C-C and C-Cl Bonds by Pd and PdCl(-). Understanding Anion Assistance in C-X Bond Activation. Journal of chemical theory and computation 91 26641300
2005 Phosducin-like protein regulates G-protein betagamma folding by interaction with tailless complex polypeptide-1alpha: dephosphorylation or splicing of PhLP turns the switch toward regulation of Gbetagamma folding. The Journal of biological chemistry 45 15745879
2022 Oxidative DNA cleavage mediated by a new unexpected [Pd(BAPP)][PdCl4] complex (BAPP = 1,4-bis(3-aminopropyl)piperazine): crystal structure, DNA binding and cytotoxic behavior. RSC advances 22 35425175
2002 Structure of the functional domain of the major grass-pollen allergen Phlp 5b. Acta crystallographica. Section D, Biological crystallography 22 12077438
2020 Unprecedented formation of palladium(II)-pyrazole based thiourea from chromone thiosemicarbazone and [PdCl2(PPh3)2]: Interaction with biomolecules and apoptosis through mitochondrial signaling pathway. Journal of inorganic biochemistry 19 31981770
2000 Quantification of the tissue levels and function of the G-protein regulator phosducin-like protein (PhlP). Naunyn-Schmiedeberg's archives of pharmacology 19 11111839
1998 Phosducin-like protein (PhLP), a regulator of G beta gamma function, interacts with the proteasomal protein SUG1. Biochimica et biophysica acta 19 9551090
2002 A novel germ line-specific gene of the phosducin-like protein (PhLP) family. A meiotic function conserved from yeast to mice. The Journal of biological chemistry 17 12424248
2020 PNA-Based Dynamic Combinatorial Libraries (PDCL) and screening of lectins. Bioorganic & medicinal chemistry 14 32241620
2004 Synthesis, characterisation, activities, cell uptake and DNA binding of [[trans-PtCl(NH3)2] [mu-(H2N(CH2)6NH2)] [trans-PdCl(NH3)2](NO3)Cl. European journal of medicinal chemistry 12 15501544
2021 PdCl2-catalyzed synthesis of a new class of isocoumarin derivatives containing aminosulfonyl / aminocarboxamide moiety: First identification of a isocoumarin based PDE4 inhibitor. European journal of medicinal chemistry 11 33992926
1998 Specificity of base substitution mutations induced by the dietary carcinogens 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhlP) and 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) in Salmonella. Environmental and molecular mutagenesis 8 9654241
2016 Apoptosis-inducing Effect of a Palladium(II) Complex-[PdCl(terpy)](sac).2H2O] on Ehrlich Ascites Carcinoma (EAC) in Mice. In vivo (Athens, Greece) 7 27381609
2001 Synthesis of beta-P,N aminophosphines and coordination chemistry to Pd(II). X-ray structures of [PdCl2(Ph2PCH(Ph)NHPh-kappaP,kappaN)] and PdCl(eta3-C3H5)(Ph2PCH2CH(Ph)NHPh-kappaP)]. Inorganic chemistry 5 11261970
2021 Low-dimensional compounds containing bioactive ligands. Part XVII: Synthesis, structural, spectral and biological properties of hybrid organic-inorganic complexes based on [PdCl4]2- with derivatives of 8-hydroxyquinolinium. Journal of inorganic biochemistry 4 34999425
2018 Characterization of a protozoan Phosducin-like protein-3 (PhLP-3) reveals conserved redox activity. PloS one 4 30596727
2026 Insertion of SnCl2 into the Pd-Cl bond: mechanistic elucidation and antitumor evaluation of trichlorostannyl palladium-NHC allyl complexes in ovarian cancer models. Dalton transactions (Cambridge, England : 2003) 0 41944661

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