DHDDS source guide

The review preserves all 24 imported annotation records and the four UniProt product identities. The current QuickGO source contains the same annotation tuples. It applies the project curation instructions: use evidence-supported specific replacements and retain positive generic interactions when a more informative molecular function cannot be justified.

Catalysis and complex architecture

PMID:25066056(https://pmc.ncbi.nlm.nih.gov/articles/PMC4161961/), Results on evolutionary conservation and Figure 2, tests human hCIT/DHDDS with NgBR in a yeast strain lacking endogenous cis-prenyltransferase subunits. Co-translated pairs made long-chain products; separately translated proteins mixed afterwards did not reproduce activity. The human DHDDS K42E experiments in the later Results show reduced activity in that system. The title's emphasis on NUS1 does not make DHDDS an untested paralog.

PMID:28842490(https://pmc.ncbi.nlm.nih.gov/articles/PMC5655512/), Results on purification and substrate binding and the corresponding Experimental procedures, uses human complex purified from Expi293F membranes. Both subunits contribute to the reaction. Its Results explicitly reports yeast rescue with Q86SQ9-1 and -2 but not -3, with those comparisons described as data not shown. A tolerated N-terminal hCIT tag, disruptive C-terminal tag, and internal NgBR tag are distinct engineered constructs. This limited rescue result does not establish that isoform 3 is universally inactive, and isoform 4 was not tested.

PMID:32817466(https://pmc.ncbi.nlm.nih.gov/articles/PMC7456142/), structural Results, subunit-interface mutations and Methods, resolves DHDDS 1–333 with NgBR 79–293. IPP occupies both crystal sites. FPP was used with radiolabeled IPP in activity assays; it is not the ligand observed in that crystal. Product TLC follows dephosphorylation, so the displayed polyprenols are not evidence that the enzyme immediately releases an unphosphorylated product. Product lengths are distributed and context dependent.

PMID:33077723(https://pmc.ncbi.nlm.nih.gov/articles/PMC7573591/), assembly and active-site Results plus native MS, SEC-MALS, crosslinking and enzyme Methods, establishes a 2:2 assembly using full-length human DHDDS and engineered soluble NgBR. It shows FPP/Mg and phosphate at the second crystal site. The DHDDS pocket is completed by the NUS1 C-terminal tail. The heterodimeric unit in the earlier structure is compatible with this dimer-of-heterodimers assembly. Neither study establishes equal activity for all four natural DHDDS products.

PMID:35584224(https://pubmed.ncbi.nlm.nih.gov/35584224/), Results on substrate-associated states, limited proteolysis, fluorescent substrate and nanodiscs, plus Protein expression and purification and Yeast complementation assay, further tests full-length human DHDDS with engineered NgBR. These experiments support an N-terminal conformational mechanism and membrane coupling, without establishing an additional independent molecular activity.

The immediate product is unsaturated polyprenyl/dehydrodolichyl diphosphate. DHDDS catalyses precursor formation used in dolichol and dolichyl phosphate biosynthesis; it does not catalyse all subsequent reduction or phosphorylation reactions. The existing GO-CAM 66c7d41500000080 explicitly places Q86SQ9's GO:0045547 activity at the ER membrane in GO:0043048. GO:0006489 and GO:0043048 are both represented in the catalytic core as established pathway-participation assertions. Neither is an ancestor of the other in the checked ontology. The immediate product distinction does not exclude the enzyme from pathways to subsequent dolichol derivatives. No NEW process annotation is proposed.

Location and interactions

PMID:14652022(https://pubmed.ncbi.nlm.nih.gov/14652022/) remains abstract-only in this assessment. The abstract explicitly describes human brain cDNA, CHO-cell microsomal activity and calnexin colocalization. These details support the existing ER-membrane assertion, with curator deference for unrecovered finer methods. PMID:21572394(https://pmc.ncbi.nlm.nih.gov/articles/PMC3116281/), Figure 7 and Cis-PT assays, independently shows tagged hCIT–NgBR association and membrane-fraction activity. Figure 7C reports reduced hCIT abundance after NgBR knockdown but unchanged relative membrane association; NgBR is therefore not shown to be its sole membrane-targeting determinant.

The BioPlex PMID:33961781 original, Clone Construction and Affinity-Purification Mass Spectrometry, uses sequence-verified human ORFs with C-terminal FLAG-HA baits. The public IntAct DHDDS records contain Q86SQ9–Q96E22 pairs IM-29278-16507 and IM-29278-28587 in HEK293T and IM-29278-26011 in HCT116. Both participant sequence/taxon identifiers match canonical human proteins. These positive AP-MS records show co-complex association. The independent structure and interface assays establish the same pair's heterodimeric unit, meeting GO:0046982; AP-MS alone is not a stoichiometric or purified binary-binding assay. An interaction identifier can also occur on another expanded pair, so partner identity and publication are essential parts of the lookup.

PMID:15110773(https://pubmed.ncbi.nlm.nih.gov/15110773/) remains abstract-only. It reports full-length human DHDDS as yeast two-hybrid bait and an in-vitro co-immunoprecipitation confirmation with NPC2. That positive evidence is retained as non-core. NPC2's soluble cholesterol-transfer function is not a demonstrated DHDDS activity; native topology and physiological importance remain unresolved. The separate NgBR–NPC2 experiments in PMID:21572394 are not substituted for DHDDS assays.

Inferred and pathway sources

The PANTHER PTHR10291 tree places human Q86SQ9 beneath PTN000033324 (specific cis-prenyltransferase and polyprenol biosynthesis), PTN000033327 (ER) and PTN000815958 (complex membership). The literal IBDs and target lineage were inspected. Bacterial descendant evidence for conserved polyprenol precursor synthesis does not imply a bacterial cell-wall role in humans. Human self-evidence is legitimate support for ancestral placement, not circularity. The ER refinement adds independently supported membrane specificity.

The InterPro2GO mapping maps IPR001441, IPR018520 and IPR036424 to the broad alkyl-transferase activity. The human substrate assays permit the specific GO:0045547 replacement; the broad mapping is not itself biologically false. The EC:2.5.1.87/RHEA:53008 and UniProt SL-0097 mappings agree with the demonstrated reaction and compartment.

The normal Reactome event R-HSA-4419978 links catalyst 4419984, complex R-HSA-6806947 and DHDDS component R-HSA-4419977. The component is Q86SQ9 at the ER membrane. The disease event R-HSA-4755545 links catalyst 9631910, complex R-HSA-9631761 and K42E component R-HSA-4755568. The latter is a mutant model, not a separate wild-type localization experiment. The location is retained with independent human evidence; no mutant catalytic defect is transferred to wild type.

Product and access limits

Official Q86SQ9 products reconstruct to 333, 334, 294 and 299 residues. Product 2 inserts one glutamine, product 3 lacks residues 109–147, and product 4 replaces residues 147–181 with one asparagine, relative to the canonical sequence. These identities are preserved. Only the stated isoform rescue tests and canonical recombinant constructs support activity claims; length alone does not establish functional equivalence.

Normal publication flags remain unchanged. Full originals for PMID:28842490 and PMID:32817466 were independently recovered despite abstract-only cache flags. PMID:21572394 was also read from its original, while PMID:14652022 and PMID:15110773 remain abstract-only. The source links and section locators above distinguish those scopes. Automated provider research failed authentication/quota checks; no provider report was invented.

2026-10-17 review follow-up

The full 15-word active-site quotation already preserved in the notes comes from PMID:33077723, Results on the hydrophobic active-site tunnel, Figure 4c–d and concluding reference to Figure 2. It places the substrate-binding pocket in DHDDS and contrasts it with the closed NgBR region. Results on tetramerization and the Discussion separately identify the NgBR C-terminal RxG contribution across the interface. The core's short location-specific excerpt points to that full contextual anchor without repeating it; the cooperative catalytic architecture is retained.

The same original's Figure 1a depicts the precursor reaction, Figure 1d reports activity, and Enzyme kinetics specifies FPP and radiolabeled IPP incorporation. These support the process row through explicit source locators and paraphrased chemistry, without a second quotation. Both dolichyl-diphosphate and dolichyl-monophosphate pathway terms remain supported; this does not equate saturated dolichol derivatives with the immediate unsaturated product.

The full PMID:25066056 Results on conserved heteromeric organization and Figure 2 provide the co-translation anchor now shown on the specific activity row. The broader prenyltransferase row cites the same source without repeating it. Human hCIT/DHDDS and NgBR are among the tested pairs; the result is not inferred merely from the paper's title or yeast proteins.