| Category | Identity | Protein features/domains | Enzymatic activity & specificity | Reaction type/EC context | Localization | Regulators of assembly/disassembly | Genetic phenotypes | Links to small-RNA pathways/nuage organization | Quantitative data points | Key references with year | DOI URL |
|---|---|---|---|---|---|---|---|---|---|---|---|
| pgl-3 / PGL-3 summary | **Gene/protein identity:** *Caenorhabditis elegans* **pgl-3** = ORF **C18G1.4**; protein **PGL-3**; UniProt **G5EBV6**. Identified as a PGL-family P-granule component and paralog of PGL-1; acts redundantly with PGL-1 in germline development (pqac-00000001, pqac-00000002, pqac-00000004) | **693 aa** predicted protein; close to PGL-1 (**62% identity, 77% similarity**); contains C-terminal **RGG box** with **59 aa** and **6 RGG repeats**, consistent with RNA-binding potential. Proteolysis mapped a PGL-3 **dimerization domain (DD)** to roughly **aa 205–447**; DD-related interface residues are conserved with PGL-1 (pqac-00000001, pqac-00000004, pqac-00000010, pqac-00000024) | PGL proteins are **base-specific, single-stranded RNases**. Direct biochemical work established guanosine-specific ssRNA endonuclease activity for PGL-1 DD; **Ce-PGL-3 also showed RNA cleavage activity**, indicating conserved RNase function in PGL family. Cleavage requires **ssRNA**, a **G** residue, and the **2′-OH**; DNA or **2′-fluoroguanosine** blocks activity. RNase-defective **Q342A** in PGL-1 abolishes cleavage without disrupting dimerization/RNA binding, supporting DD-centered catalysis (pqac-00000008, pqac-00000009, pqac-00000011, pqac-00000012, pqac-00000013) | UniProt assigns **EC 4.6.1.24** / guanyl-specific ribonuclease context; primary literature supports a **guanosine-specific ssRNA endonuclease** activity for the PGL family, mechanistically resembling **RNase T1-like** cleavage specificity but much weaker. Assays were **metal-independent** under tested conditions (**5 mM EDTA**, MgCl2, MnCl2 had no major effect) (pqac-00000008, pqac-00000009, pqac-00000011, pqac-00000013) | Constitutive component of **P granules** in embryos and adult germ line; enriched in germline blastomeres after maternal deposition and in larval/adult germ line, especially pachytene region. P granules are typically **perinuclear** during germline development, become cytoplasmic during oogenesis, and reattach in embryos. P granules contact most nuclear pores; in modern imaging, about **75%** of nuclear pores associate with P granules (pqac-00000004, pqac-00000015, pqac-00000016, pqac-00000018, pqac-00000021) | PGL-3/P granule assembly depends on a broader granule network: **PGL-1 and PGL-3 self-associate and nucleate granule formation**; **GLH-1/GLH-4** promote perinuclear localization; **DEPS-1** functions upstream in assembly; **MEG-3/MEG-4** promote embryonic assembly, while **MEG-1/MEG-2** contribute more to disassembly; **MBK-2** kinase and **PPTR-1/PP2A** regulate dissolution/condensation through phosphorylation pathways. P granules dissolve with heat stress and **1,6-hexanediol** (pqac-00000005, pqac-00000014, pqac-00000017, pqac-00000019, pqac-00000020) | **pgl-3 single mutants** show little obvious germline defect, but **pgl-1; pgl-3** double loss strongly enhances sterility and defects in germline proliferation/gametogenesis. Broad P-granule depletion causes sterile adults and germline-to-soma reprogramming. In quadruple RNAi against **pgl-1, pgl-3, glh-1, glh-4**, **40/100 F1** adults were sterile (range **27–89%**), and sterile germ lines lost detectable perinuclear P-granule organization (pqac-00000000, pqac-00000003, pqac-00000005, pqac-00000020) | PGL-3 is a **constitutive P-compartment** factor in perinuclear nuage that interfaces with RNA surveillance/small-RNA pathways. Recent work places P granules as the first compartment receiving newly exported RNA, with adjacent Z, SIMR, Mutator, and E granules handling distinct RNA silencing steps. Disrupting perinuclear germ granules alters piRNA/22G-RNA pathways and transcriptomes; P-granule components including **pgl-3** were used in “P-granule RNAi” paradigms to test granule function (pqac-00000021, pqac-00000023, pqac-00000025, pqac-00000026, pqac-00000029) | **13.9-fold** reduction of pgl-3 transcript in quadruple P-granule RNAi germ lines; paired reductions for pgl-1/glh-1/glh-4 were **24.7-, 2.0-, 3.7-fold**. In enzymology, PGL-1 DD cleavage used about **3 μM** enzyme versus **1.2 nM** RNase T1 for similar pattern (~**2,500-fold** higher concentration), highlighting modest catalytic power. Recent germ-granule organization work quantified **75%** nuclear-pore association with P granules. In eggd-1 mutants, perinuclear PGL-1 granule mean volume dropped from **0.482 to 0.183 μm3** (**2.64-fold smaller**) and could form rachis aggregates up to **25 μm3**; although measured on PGL-1, these values reflect the PGL-3-containing P-granule system. In 2024 E-granule work, **1504** and **1282** genes lost ≥2-fold siRNAs in **egc-1(-)** and **elli-1(-)**, respectively, underscoring subcompartment specialization adjacent to P granules (pqac-00000008, pqac-00000013, pqac-00000020, pqac-00000021, pqac-00000025, pqac-00000026, pqac-00000028) | Kawasaki et al. **2004**; Updike et al. **2014**; Aoki et al. **2016**; Uebel et al. **2023**; Price et al. **2023**; Chen et al. **2024** (pqac-00000000, pqac-00000005, pqac-00000012, pqac-00000021, pqac-00000025, pqac-00000029) | https://doi.org/10.1534/genetics.103.023093 ; https://doi.org/10.1016/j.cub.2014.03.015 ; https://doi.org/10.1073/pnas.1524400113 ; https://doi.org/10.1242/dev.202284 ; https://doi.org/10.1038/s41467-023-41556-4 ; https://doi.org/10.1038/s41467-024-50027-3 |


*Table: This table summarizes the identity, molecular features, enzymatic activity, localization, phenotypes, and modern germ-granule context for C. elegans PGL-3. It condenses both foundational and 2023–2024 evidence into a single citation-linked reference for report writing.*