RFT1: Key Flippase in N-Linked Glycosylation and Its Functional Annotation OpenAI o3-deep-research-2025-06-26 125 citations 2025-12-27T21:44:16.998777

RFT1: Key Flippase in N-Linked Glycosylation and Its Functional Annotation

Background: N-Linked Glycosylation and the Role of RFT1

N-linked glycosylation is a fundamental process in which a pre-assembled oligosaccharide is attached to specific asparagine residues of nascent proteins in the endoplasmic reticulum (ER) (pmc.ncbi.nlm.nih.gov). This oligosaccharide precursor – a 14-sugar Glc3Man9GlcNAc2 structure in humans – is built on a lipid carrier (dolichol pyrophosphate) via a stepwise pathway (pmc.ncbi.nlm.nih.gov). The first seven sugars (two N-acetylglucosamines and five mannoses) are assembled on the cytosolic face of the ER, forming the intermediate Man5GlcNAc2-PP-dolichol (also called M5-DLO or a “heptasaccharide” lipid intermediate) (pmc.ncbi.nlm.nih.gov). This intermediate must then be flipped or translocated across the ER membrane into the lumen, where the remaining seven sugars (four mannoses and three glucoses) are added to complete the precursor (pmc.ncbi.nlm.nih.gov). The protein RFT1 – identified in yeast around 2002 as “Required for Flipping of Man5GlcNAc2-PP-dolichol” – is the membrane transporter responsible for this translocation step (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). In other words, RFT1 functions as the ER flippase (or scramblase) that flips the lipid-linked oligosaccharide from the cytosolic leaflet to the luminal leaflet of the ER membrane, a step essential for N-glycan biosynthesis (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This role is critical: without RFT1, the oligosaccharide cannot reach the lumen and be matured or transferred to proteins, stalling the entire N-glycosylation pathway (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).

Key Concept – Lipid-Linked Oligosaccharide Flipping: RFT1 specifically translocates the Man5GlcNAc2-PP-dolichol intermediate across the ER membrane. Genetic studies first implicated RFT1 in this process (Helenius et al., 2002) when yeast lacking Rft1 accumulated the intermediate and failed to complete glycosylation (pmc.ncbi.nlm.nih.gov). Correspondingly, when the human RFT1 gene is nonfunctional, cells also accumulate Man5GlcNAc2>-PP-dolichol on the cytosolic side, underscoring that the flipping step is blocked (pmc.ncbi.nlm.nih.gov). Biochemically, this flipping is ATP-independent – RFT1 acts as a lipid scramblase that facilitates the equilibrative movement of the glycolipid between membrane leaflets (pmc.ncbi.nlm.nih.gov). It exhibits high specificity for the dolichol-linked heptasaccharide, ensuring that this exact precursor (and not unrelated lipids) is efficiently translocated (pmc.ncbi.nlm.nih.gov). After flipping by RFT1, the complete Glc3Man9GlcNAc2 glycan is assembled in the lumen and then transferred en bloc to proteins by oligosaccharyltransferase (OST) (pmc.ncbi.nlm.nih.gov). Thus, RFT1’s primary function is to enable the key translocation step that connects cytosolic and luminal phases of N-glycan assembly, a role conserved across eukaryotic life (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).

Molecular Characteristics and Localization of RFT1

Human RFT1 (UniProt Q96AA3) is an ER-resident multi-pass membrane protein consisting of 541 amino acids. Both its N-terminus and C-terminus face the cytosolic side of the ER membrane (pmc.ncbi.nlm.nih.gov). Topology studies and predictive modeling indicate that RFT1 spans the membrane ~14 times, forming a complex transmembrane structure (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Notably, RFT1 has no confirmed glycosylation sites of its own (it is not N-glycosylated), consistent with an orientation where any luminal loops are short or inaccessible for glycan attachment (pmc.ncbi.nlm.nih.gov). The protein belongs to the RFT1 family (Pfam PF04506), an evolutionarily conserved family of ER proteins found in virtually all eukaryotes (from yeast to humans) (pmc.ncbi.nlm.nih.gov). Despite low sequence identity between distant orthologs – for example, human RFT1 shares only ~22% amino-acid identity with yeast Rft1 – these proteins are functionally interchangeable, indicating strong conservation at the functional level (pmc.ncbi.nlm.nih.gov). Experiments have shown that human RFT1 can complement an RFT1 deletion in yeast, restoring normal growth and glycosylation, whereas a disease-mutant form of human RFT1 cannot (pmc.ncbi.nlm.nih.gov). This cross-species complementation underscores that the core function of RFT1 has been preserved even if the primary sequences diverged significantly (pmc.ncbi.nlm.nih.gov).

At the structural level, recent analyses suggest that RFT1 adopts a fold reminiscent of the MOP superfamily of transporters (the Multidrug/Oligosaccharidyl-lipid/Polysaccharide flippase family) (pmc.ncbi.nlm.nih.gov). In fact, computational models (AlphaFold2, 2024) indicate RFT1’s transmembrane domain is organized into two symmetric halves (each ~7 TM helices) forming a hydrophilic central cavity (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This architecture is strikingly similar to known lipid flippases such as bacterial MurJ, which uses an alternating-access mechanism to flip lipid-linked peptidoglycan precursors (pmc.ncbi.nlm.nih.gov). The RFT1 model appears in an inward-open conformation, with a water-exposed cavity facing the cytosol that likely accommodates the Man5GlcNAc2-PP-dolichol substrate (pmc.ncbi.nlm.nih.gov). Key conserved residues line this cavity and are thought to mediate substrate binding and translocation (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Notably, most missense mutations identified in patients with RFT1 deficiency cluster in these conserved regions of the protein, highlighting their importance for function (pmc.ncbi.nlm.nih.gov). Together, these structural features support a model in which RFT1 “grabs” the heptasaccharide-pyrophosphate dolichol on the cytosolic side and swivels to release it on the luminal side – a classic alternating-access transport mechanism analogous to other known lipid flippases (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Consistent with this idea, purified RFT1 protein reconstituted into liposomes is sufficient to mediate flipping without any other ER factors, suggesting RFT1 alone forms the active translocation pore or channel for the lipid-linked oligosaccharide (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).

Cellular Localization: RFT1 is an integral membrane protein of the endoplasmic reticulum. Endogenous RFT1 localizes to the ER membrane where N-glycan assembly occurs (pmc.ncbi.nlm.nih.gov). It is not found in the plasma membrane or other organelles, as its function is tightly linked to the ER’s dolichol pathway. In mammalian cells, RFT1’s expression is essential for viability – cells lacking RFT1 cannot survive due to failure of protein glycosylation (pmc.ncbi.nlm.nih.gov). Similarly, yeast RFT1 is an essential gene under normal conditions (pmc.ncbi.nlm.nih.gov). (One notable exception is Trypanosoma brucei, a parasitic protozoan where RFT1 is surprisingly non-essential for growth (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This organism appears to have an alternate mechanism or bypass for LLO flipping, as discussed below.) Overall, RFT1 predominantly resides in ER membranes and carries out its transporter function co-translationally as the LLO is synthesized, ensuring that glycan assembly can seamlessly continue on the luminal side.

Functional Evidence and Mechanism: Flipping the Lipid-Linked Oligosaccharide

Biochemical and genetic evidence strongly indicate that RFT1’s primary substrate is the lipid-linked heptasaccharide Man5GlcNAc2-PP-dolichol. In a landmark human study (Haeuptle et al., 2008), a young patient was found to accumulate this exact intermediate in cells due to a defective RFT1 gene (pmc.ncbi.nlm.nih.gov). The accumulation of Man5GlcNAc2-PP-dolichol on the cytosolic side (with a corresponding shortage of fully assembled Glc3Man9GlcNAc2 in the lumen) is a clear biochemical signature of a flipping blockade (pmc.ncbi.nlm.nih.gov). Restoring a functional RFT1 in these patient cells allowed the intermediate to be properly utilized and normal glycosylation to resume (pmc.ncbi.nlm.nih.gov). This finding mirrors earlier yeast genetic studies (Helenius et al., 2002) in which rft1 mutants accumulated the same heptasaccharide and could not complete N-glycosylation (pmc.ncbi.nlm.nih.gov). Together, these results established that RFT1 is required for translocating Man5GlcNAc2-PP-dolichol from the cytoplasmic to luminal ER leaflet**, a step that is indispensable for assembling the complete N-glycan precursor (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Without RFT1, the downstream ER-localized glycosyltransferases (Alg3, Alg9, Alg12 for mannose and Alg6/8/10 for glucose additions) cannot access the substrate, leading to under-glycosylated proteins and severe cellular dysfunction (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).

Mechanistically, RFT1 appears to function as a selective scramblase. It does not hydrolyze ATP or use any obvious energy source; instead, it facilitates the flip-flop of the pyrophosphate-linked oligosaccharide down its concentration gradient in a highly selective manner (pmc.ncbi.nlm.nih.gov). Early studies suggested the existence of an ATP-independent flippase activity in ER membranes specific for the LLO intermediate (pmc.ncbi.nlm.nih.gov). RFT1 fits this profile: it likely lowers the energy barrier for the charged, bulky Man5GlcNAc2-PP-dolichol to traverse the hydrophobic membrane. Importantly, this specificity distinguishes RFT1 from general lipid scramblases that indiscriminately equilibrate lipids. In vitro assays have confirmed that RFT1 does not flip simpler lipid phosphates (like phosphatidylcholine) but does translocate the dolichol-linked oligosaccharide (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This agrees with the idea that RFT1’s transmembrane cavity is tailored to recognize the polyprenol-pyrophosphate glycan headgroup. Intriguingly, some evidence suggests RFT1 might also assist in flipping other lipid-linked glycans. For example, a study in T. brucei (Gottier et al., 2017) found that loss of RFT1 affected GPI anchor glycosylation, implying RFT1 may partake in translocation of the glycolipid intermediates of GPI anchor biosynthesis as well (pmc.ncbi.nlm.nih.gov). While human RFT1’s involvement in GPI precursor flipping remains less clear, this observation raises the possibility that RFT1’s “substrate” could include multiple glycolipid types in organisms that lack alternative flippases. Nonetheless, the best-established and primary role of RFT1 in human cells is the flipping of the N-glycan lipid precursor Man5GlcNAc2-PP-Dol, a prerequisite for proper N-linked protein glycosylation (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).

Historical Controversy and Recent Advances (2023–2024)

For over two decades, the identity of the ER LLO flippase was a subject of debate (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Initial genetic evidence in yeast (2002) and the first human case (2008) strongly pointed to RFT1 as the required flippase, since RFT1 loss caused the expected glycosylation defect in vivo (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). However, subsequent biochemical studies in 2008–2009 challenged this interpretation. In 2008, Menon and colleagues reconstituted ER membrane vesicles and reported that Man5GlcNAc2-PP-Dol flipping occurred even in the apparent absence of RFT1, suggesting “a specific ER protein(s), but not Rft1, is required to flip” the LLO precursor (www.nature.com). Similarly, a 2009 study by Rush et al. found that yeast microsomes with greatly reduced Rft1 still showed normal translocation of the heptasaccharide, implying redundant or RFT1-independent flipping activity (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). These findings led to a hypothesis that RFT1 might play an indirect or accessory role (perhaps as a chaperone for the LLO or in maintaining membrane homeostasis) rather than being the flippase itself (www.nature.com). The mystery deepened when Jelk et al. (2013) discovered that Trypanosoma brucei can survive without any RFT1, yet still glycosylate its proteins – evidence that an alternate flippase exists in that organism (pmc.ncbi.nlm.nih.gov). By the mid-2010s, RFT1 was the only protein ever implicated in LLO translocation, but definitive proof of its direct role was lacking and many experts remained skeptical of its function (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Reviews of congenital glycosylation disorders even highlighted the “enigmatic” nature of RFT1, noting that its essential role in most eukaryotes was clear despite the contradictory in vitro data (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).

Resolution – Direct Flippase Proof: The long-standing controversy was resolved by new research in 2023–2024. In June 2024, a breakthrough study in Nature Communications by Shuai Chen et al. provided unequivocal evidence that RFT1 itself catalyzes lipid-linked oligosaccharide flipping (pmc.ncbi.nlm.nih.gov). The researchers purified RFT1 (from yeast and human) and reconstituted it into artificial liposomes, then monitored transport of a fluorescently labeled Man5GlcNAc2-PP-dolichol analog. They demonstrated that RFT1 alone is sufficient to translocate the oligosaccharide across the bilayer in vitro (pmc.ncbi.nlm.nih.gov). This work showed substrate specificity matching the in vivo requirements – RFT1 robustly flipped the full pyrophosphate-linked heptasaccharide, whereas simpler dolichol-phosphate sugars were not transported (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). In the same assays, an unrelated control protein could not substitute for RFT1, confirming the activity was intrinsic to RFT1. Notably, the Nature Communications study also tested an archaeal protein (Haloarcula Agl23) that had been discovered via a genetic suppressor screen: remarkably, Agl23 – which has no sequence homology to RFT1 – could flip the LLO intermediate just like RFT1 (pmc.ncbi.nlm.nih.gov). Agl23 had been found capable of rescuing yeast lacking RFT1, and in the reconstituted system it, too, catalyzed efficient flipping of Man5GlcNAc2-PP-dolichol (or a polyprenol analog) (pmc.ncbi.nlm.nih.gov). This provided independent validation that flipping can be accomplished by at least two structurally distinct proteins, underscoring that it is flippase activity per se that is critical, whether provided by RFT1 or a surrogate (pmc.ncbi.nlm.nih.gov). Together, these results “unequivocally support the idea that Rft1, from both yeast and human, is directly responsible” for translocating the LLO intermediate in eukaryotic cells (pmc.ncbi.nlm.nih.gov).

Concurrently, other researchers have solidified our understanding of RFT1’s structure-function. In July 2024, a study in Journal of Biological Chemistry (Hirata et al., 2024) provided a detailed molecular characterization of human RFT1 using yeast as a model system (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This work confirmed that RFT1 is a multi-spanning ER protein with no glycosylation, and identified several critical residues required for its function by testing mutant variants in yeast (pmc.ncbi.nlm.nih.gov). The JBC study’s structural analysis reinforced the similarity between RFT1 and bacterial flippases like MurJ, lending a strong theoretical framework for how RFT1 works (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). With modern tools, the authors could finally reconcile the old discrepancies: they suggested that earlier in vitro assays likely had unidentified ER scramblases keeping partial flipping activity in RFT1-depleted preparations, whereas the 2024 reconstitution used highly purified components to attribute activity specifically to RFT1 (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). In summary, as of 2024, consensus has been reached that RFT1 is the bona fide ER flippase for the N-glycan precursor, resolving a decades-long question in cell biology (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This resolution fills an important gap in the canonical N-glycosylation pathway and is hailed as a significant advance in our understanding of membrane transport mechanisms in glycoprotein biosynthesis (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).

Clinical Significance: RFT1-Congenital Disorder of Glycosylation (CDG-In)

RFT1 deficiency in humans causes a severe congenital disorder of glycosylation, underscoring the protein’s indispensable role in vivo (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). The first patient with RFT1-CDG was reported in 2008 (an infant with a homozygous RFT1 missense mutation, p.R67C) and presented with a profound multisystem disease (pmc.ncbi.nlm.nih.gov). Biochemical analysis of this patient’s cells revealed an intracellular build-up of Man5GlcNAc2-PP-dolichol and abnormally under-glycosylated serum glycoproteins, directly linking the RFT1 mutation to a defect in N-linked glycan assembly (pmc.ncbi.nlm.nih.gov). Expression of normal RFT1 cDNA in the patient’s fibroblasts rescued the glycosylation defect, proving causality of the RFT1 mutation (pmc.ncbi.nlm.nih.gov). Following this discovery, a handful of additional cases were identified worldwide (three new cases were described by 2009), and the disorder has been designated “RFT1-CDG” or CDG type In (CDG-In, in the original nomenclature) (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). RFT1-CDG is inherited in an autosomal recessive manner and is extremely rare – only a few families have been documented in the literature (pmc.ncbi.nlm.nih.gov).

Clinically, RFT1-CDG patients exhibit the hallmark features of many N-glycosylation disorders, combined with some distinctive symptoms. Infants typically show failure to thrive, hypotonia (low muscle tone), and developmental delays from early on (pmc.ncbi.nlm.nih.gov). Neurological problems are prominent, including seizures or myoclonic jerks and intellectual disability (pmc.ncbi.nlm.nih.gov). Organ systems such as the liver and gut can be affected, and dysmorphic features or skeletal abnormalities are sometimes noted, reflecting the systemic importance of glycoproteins (pmc.ncbi.nlm.nih.gov). Strikingly, sensorineural deafness has been observed in all reported RFT1-CDG patients – an unusual feature not seen in most other CDG subtypes (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). This consistent deafness, alongside the severe neurodevelopmental impairment, suggests that certain cell types (e.g. inner ear neurons and brain cells) are especially sensitive to defects in the LLO flipping step (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Indeed, researchers have noted that RFT1-CDG is “mainly a neurological disorder,” with the ear pathology as a notable clue (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). There is currently no cure for RFT1-CDG; management is supportive and focuses on treating symptoms (for example, anti-seizure medications and nutritional support). Early death in childhood is common in the severe cases reported (pmc.ncbi.nlm.nih.gov). The identification of RFT1-CDG has, however, enabled genetic diagnosis for affected families. RFT1 gene sequencing is now included in CDG diagnostic panels (listed as CDG-1N in genetic testing registries) (www.ncbi.nlm.nih.gov). This allows for carrier testing and prenatal diagnosis, which are important given the recessive inheritance and high medical burden of the disease. RFT1-CDG is one of more than 30 known genetic defects in the N-linked glycosylation pathway (pmc.ncbi.nlm.nih.gov), and each such discovery (RFT1 included) has provided valuable insight into human glycan biosynthesis. In particular, RFT1-CDG cases offered in vivo confirmation that the Man5GlcNAc2-PP-Dol flippase step is critically important for human development (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov).

Current Applications and Future Directions

The elucidation of RFT1’s function has several important applications in biomedicine and biotechnology. Diagnostic Medicine: As described above, knowing the molecular basis of RFT1-CDG allows clinicians to diagnose this disorder via genetic testing and abnormal glycosylation screening (e.g. transferrin isoform analysis) (pmc.ncbi.nlm.nih.gov). For families affected by RFT1-CDG, genetic counseling and early intervention become possible now that the gene is identified. Moreover, RFT1-CDG stands as a model for developing therapies for glycosylation disorders. One experimental approach demonstrated in 2008 was to use a lentiviral vector expressing wild-type RFT1 to “cure” patient cells in culture (pmc.ncbi.nlm.nih.gov). This gene therapy concept – replacing the defective flippase gene – successfully restored normal glycan profiles in vitro (pmc.ncbi.nlm.nih.gov). While actual gene therapy in patients would face significant hurdles, this result provides a proof-of-principle that correcting the flip defect can rescue cell function. As gene delivery techniques improve, RFT1 might be considered a candidate for future gene therapy trials in CDG (especially if a patient presents with a milder, partially active mutation that could be complemented). Additionally, understanding RFT1’s activity enables screening for small molecules or pharmacological chaperones that might stabilize certain mutant RFT1 proteins. If a partial loss-of-function mutant is misfolded, a drug that improves its folding could restore some flipping activity – a strategy being explored for other protein-misfolding CDGs (pmc.ncbi.nlm.nih.gov).

Research and Biotechnology: The definitive identification of RFT1 as the LLO flippase also has practical implications for research and bioengineering. In glycobiology research, the availability of an in vitro flipping assay (thanks to purified RFT1 reconstitution) is a significant advancement (pmc.ncbi.nlm.nih.gov). This assay can be used to interrogate the mechanism of translocation in detail – for instance, to determine how fast RFT1 flips the lipid, whether any ion gradients or membrane conditions modulate its activity, and whether accessory proteins influence efficiency. It also opens the door to high-resolution structural studies (e.g. cryo-EM efforts) now that a functional preparation of RFT1 is in hand. Early modeling suggests RFT1 operates via an alternating-access mechanism (pmc.ncbi.nlm.nih.gov), and future studies may capture different conformational states of RFT1 or even co-complexes with the LLO substrate. Such structural insights could be invaluable for rational drug design if one ever aims to modulate N-glycosylation (for example, tweaking glycan profiles in biotech production of therapeutic glycoproteins). In biotechnology, engineering robust N-glycosylation pathways in non-native systems (like yeast or microalgae used to produce recombinant proteins) requires a functional flippase. The confirmation that RFT1 is the required flippase means that any glyco-engineering effort must ensure RFT1 (or an equivalent activity) is present. Indeed, the discovery that an archaeal protein (Agl23) can substitute for RFT1’s function (pmc.ncbi.nlm.nih.gov) hints that there may be bioengineered solutions to bypass defects or optimize glycosylation. For instance, if a particular production strain has low endogenous flipping efficiency, introducing a more efficient flippase (perhaps a variant or a surrogate from another species) might enhance glycoprotein yield or fidelity.

Finally, RFT1’s study has broader significance in cell biology. It exemplifies how cells handle hydrophilic substrates within membranes and has stimulated comparisons to other lipid transport processes. The knowledge gained from RFT1 is informing research on analogous systems, such as flippases for GPI anchors and other glycolipids. As noted, RFT1 may not act entirely alone in living cells – there could be a network of membrane proteins ensuring all kinds of lipid-linked sugars are properly oriented. By studying RFT1, scientists are also learning how membrane topology and protein machinery co-evolved to manage complex lipid-linked reactions. In summary, the current understanding of RFT1 – solidified by recent research – not only completes the puzzle of the N-linked glycosylation pathway but also provides a foundation for medical and biotechnological advances. This ER transporter, once controversial, is now recognized as a crucial enzyme-like protein that bridges two phases of glycan assembly, with real-world impacts from diagnosing rare diseases to potentially improving biomanufacturing of glycoproteins. The ongoing research and expert analyses uniformly highlight RFT1 as “the” Man5GlcNAc2-PP-Dol flippase in eukaryotes (pmc.ncbi.nlm.nih.gov), reflecting a consensus built on decades of study and culminating in the latest findings of 2024.

References: Recent authoritative sources supporting this report include Nature Communications (June 17, 2024) which provided direct biochemical evidence for RFT1’s flippase activity (pmc.ncbi.nlm.nih.gov), and J. Biol. Chem. (July 2024) which detailed RFT1’s structure-function characteristics (pmc.ncbi.nlm.nih.gov) (pmc.ncbi.nlm.nih.gov). Foundational studies in Nature (Helenius et al., 2002) first implicated RFT1 in LLO translocation (pmc.ncbi.nlm.nih.gov), while an Am. J. Hum. Genet. paper (Feb 2008) identified RFT1 mutations in CDG patients (pmc.ncbi.nlm.nih.gov). The back-and-forth debate in the literature (e.g. Frank et al., Nature 2008 (www.nature.com), and subsequent discussions) has now been put to rest by the convergence of genetic, clinical, and biochemical data. These sources, along with others cited throughout this report, provide a comprehensive, up-to-date view of RFT1’s function, importance, and emerging applications.

Citations

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  14. AnnotationURLCitation(end_index=4532, start_index=4367, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11365447/#:~:text=the%20necessary%20glycosyltransferases%20are%20known%2C,glycosylation%20underlie')
  15. AnnotationURLCitation(end_index=4875, start_index=4729, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=topologically%20distinct,to%20the%20asparagine%20residue%20of')
  16. AnnotationURLCitation(end_index=5229, start_index=5052, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=identified%20Rft1%20by%20yeast%20genetics,vitro%20flipping%20assay%20using%20proteoliposomes')
  17. AnnotationURLCitation(end_index=5386, start_index=5230, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=translocation%20and%20demonstrate%20that%20purified,Dol%20ER%20flippase')
  18. AnnotationURLCitation(end_index=5788, start_index=5628, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11365447/#:~:text=Rft1%2C%20using%20yeast%20cells%20as,work%20on%20this%20enigmatic%20protein')
  19. AnnotationURLCitation(end_index=6065, start_index=5922, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11014557/#:~:text=Structure%20prediction%20by%20AlphaFold2%20,Scores%20range')
  20. AnnotationURLCitation(end_index=6175, start_index=6066, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11014557/#:~:text=F,7%20of%20the%2014%20TM')
  21. AnnotationURLCitation(end_index=6532, start_index=6372, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11365447/#:~:text=Rft1%2C%20using%20yeast%20cells%20as,work%20on%20this%20enigmatic%20protein')
  22. AnnotationURLCitation(end_index=6877, start_index=6700, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=identified%20Rft1%20by%20yeast%20genetics,vitro%20flipping%20assay%20using%20proteoliposomes')
  23. AnnotationURLCitation(end_index=7244, start_index=7120, title='Human RFT1 Deficiency Leads to a Disorder of N-Linked Glycosylation - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2427296/#:~:text=found%20to%20carry%20a%20homozygous,R67C')
  24. AnnotationURLCitation(end_index=7593, start_index=7421, title='Human RFT1 Deficiency Leads to a Disorder of N-Linked Glycosylation - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2427296/#:~:text=found%20to%20carry%20a%20homozygous,restoration%20of%20normal%20glycosylation%20profiles')
  25. AnnotationURLCitation(end_index=7921, start_index=7749, title='Human RFT1 Deficiency Leads to a Disorder of N-Linked Glycosylation - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2427296/#:~:text=found%20to%20carry%20a%20homozygous,restoration%20of%20normal%20glycosylation%20profiles')
  26. AnnotationURLCitation(end_index=8282, start_index=8122, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11014557/#:~:text=Both%20the%20AlphaFold2%20model%20and,MurJ%20lipid%20II%20flippases%20which')
  27. AnnotationURLCitation(end_index=8576, start_index=8467, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11014557/#:~:text=F,7%20of%20the%2014%20TM')
  28. AnnotationURLCitation(end_index=8716, start_index=8577, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11014557/#:~:text=match%20at%20L595%20potenqal%20%2858%E2%80%9361%29,Fig')
  29. AnnotationURLCitation(end_index=9056, start_index=8896, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11014557/#:~:text=Both%20the%20AlphaFold2%20model%20and,MurJ%20lipid%20II%20flippases%20which')
  30. AnnotationURLCitation(end_index=9384, start_index=9245, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11014557/#:~:text=match%20at%20L595%20potenqal%20%2858%E2%80%9361%29,Fig')
  31. AnnotationURLCitation(end_index=9649, start_index=9489, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11014557/#:~:text=Both%20the%20AlphaFold2%20model%20and,MurJ%20lipid%20II%20flippases%20which')
  32. AnnotationURLCitation(end_index=9788, start_index=9650, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11014557/#:~:text=plays%20in%20N,work%20on%20this%20enigmatic%20protein')
  33. AnnotationURLCitation(end_index=10099, start_index=9961, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11014557/#:~:text=plays%20in%20N,work%20on%20this%20enigmatic%20protein')
  34. AnnotationURLCitation(end_index=10538, start_index=10378, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11014557/#:~:text=Both%20the%20AlphaFold2%20model%20and,MurJ%20lipid%20II%20flippases%20which')
  35. AnnotationURLCitation(end_index=10678, start_index=10539, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11014557/#:~:text=match%20at%20L595%20potenqal%20%2858%E2%80%9361%29,Fig')
  36. AnnotationURLCitation(end_index=11043, start_index=10928, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=complex,independent%20flippase')
  37. AnnotationURLCitation(end_index=11218, start_index=11044, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=our%20results%20unequivocally%20support%20the,ER%20membrane%20during%20LLO%20biosynthesis')
  38. AnnotationURLCitation(end_index=11552, start_index=11392, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11365447/#:~:text=Rft1%2C%20using%20yeast%20cells%20as,work%20on%20this%20enigmatic%20protein')
  39. AnnotationURLCitation(end_index=11966, start_index=11819, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11365447/#:~:text=including%20RFT1,a%20molecular%20characterization%20of%20human')
  40. AnnotationURLCitation(end_index=12214, start_index=12037, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=identified%20Rft1%20by%20yeast%20genetics,vitro%20flipping%20assay%20using%20proteoliposomes')
  41. AnnotationURLCitation(end_index=12495, start_index=12338, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=match%20at%20L104%20yeast%20cells%2C,date%2C%20the%20identity%20of%20the')
  42. AnnotationURLCitation(end_index=12643, start_index=12496, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11365447/#:~:text=including%20RFT1,a%20molecular%20characterization%20of%20human')
  43. AnnotationURLCitation(end_index=13487, start_index=13373, title='Human RFT1 Deficiency Leads to a Disorder of N-Linked Glycosylation - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2427296/#:~:text=N,The%20human%20RFT1%20protein')
  44. AnnotationURLCitation(end_index=13860, start_index=13746, title='Human RFT1 Deficiency Leads to a Disorder of N-Linked Glycosylation - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2427296/#:~:text=N,The%20human%20RFT1%20protein')
  45. AnnotationURLCitation(end_index=14147, start_index=13997, title='Human RFT1 Deficiency Leads to a Disorder of N-Linked Glycosylation - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2427296/#:~:text=shares%2022,defect%20establishes%20the%20functional%20conservation')
  46. AnnotationURLCitation(end_index=14505, start_index=14328, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=identified%20Rft1%20by%20yeast%20genetics,vitro%20flipping%20assay%20using%20proteoliposomes')
  47. AnnotationURLCitation(end_index=14867, start_index=14753, title='Human RFT1 Deficiency Leads to a Disorder of N-Linked Glycosylation - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2427296/#:~:text=N,The%20human%20RFT1%20protein')
  48. AnnotationURLCitation(end_index=15014, start_index=14868, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=topologically%20distinct,to%20the%20asparagine%20residue%20of')
  49. AnnotationURLCitation(end_index=15361, start_index=15247, title='Human RFT1 Deficiency Leads to a Disorder of N-Linked Glycosylation - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2427296/#:~:text=N,The%20human%20RFT1%20protein')
  50. AnnotationURLCitation(end_index=15537, start_index=15362, title='RFT1 Deficiency in Three Novel CDG Patients - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC3869400/#:~:text=severe%20mental%20retardation%2C%20hypotonia%2C%20epilepsy%2C,was%20found%20in%20all%20four')
  51. AnnotationURLCitation(end_index=15982, start_index=15817, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11365447/#:~:text=the%20necessary%20glycosyltransferases%20are%20known%2C,glycosylation%20underlie')
  52. AnnotationURLCitation(end_index=16279, start_index=16114, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11365447/#:~:text=the%20necessary%20glycosyltransferases%20are%20known%2C,glycosylation%20underlie')
  53. AnnotationURLCitation(end_index=16857, start_index=16742, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=complex,independent%20flippase')
  54. AnnotationURLCitation(end_index=17032, start_index=16858, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=our%20results%20unequivocally%20support%20the,ER%20membrane%20during%20LLO%20biosynthesis')
  55. AnnotationURLCitation(end_index=17749, start_index=17503, title='RFT1 Protein Affects Glycosylphosphatidylinositol (GPI) Anchor Glycosylation - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC5247644/#:~:text=Skip%20to%20main%20content%20J,Serrano%20%5E%7B%E2%80%96%2C%7D%5E%7B%2A%2A%2C%7D%5E%7B1%7D%2C%20Peter%20B%C3%BCtikofer%20%5E%7B%E2%80%A1%2C%7D%5E%7B1%2C%7D%5E%7B2')
  56. AnnotationURLCitation(end_index=18317, start_index=18203, title='Human RFT1 Deficiency Leads to a Disorder of N-Linked Glycosylation - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2427296/#:~:text=N,The%20human%20RFT1%20protein')
  57. AnnotationURLCitation(end_index=18492, start_index=18318, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=our%20results%20unequivocally%20support%20the,ER%20membrane%20during%20LLO%20biosynthesis')
  58. AnnotationURLCitation(end_index=18767, start_index=18641, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=studies%20identified%20Rft1%20as%20the,We')
  59. AnnotationURLCitation(end_index=18945, start_index=18768, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=identified%20Rft1%20by%20yeast%20genetics,vitro%20flipping%20assay%20using%20proteoliposomes')
  60. AnnotationURLCitation(end_index=19317, start_index=19140, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=identified%20Rft1%20by%20yeast%20genetics,vitro%20flipping%20assay%20using%20proteoliposomes')
  61. AnnotationURLCitation(end_index=19432, start_index=19318, title='Human RFT1 Deficiency Leads to a Disorder of N-Linked Glycosylation - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC2427296/#:~:text=N,The%20human%20RFT1%20protein')
  62. AnnotationURLCitation(end_index=19958, start_index=19798, title='Does Rft1 flip an N-glycan lipid precursor? | Nature', type='url_citation', url='https://www.nature.com/articles/nature07165#:~:text=genetic%20evidence%20suggesting%20that%20Rft1%2C,itself%20remains%20to%20be%20identified')
  63. AnnotationURLCitation(end_index=20309, start_index=20170, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=Dol,vitro%20flipping%20assay%20using%20proteoliposomes')
  64. AnnotationURLCitation(end_index=20463, start_index=20310, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=match%20at%20L104%20yeast%20cells%2C,is%20not%20essential%20for%20at')
  65. AnnotationURLCitation(end_index=20813, start_index=20667, title='Does Rft1 flip an N-glycan lipid precursor? | Nature', type='url_citation', url='https://www.nature.com/articles/nature07165#:~:text=that%20a%20specific%20ER%20protein,itself%20remains%20to%20be%20identified')
  66. AnnotationURLCitation(end_index=21183, start_index=21026, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=yeast%20cells%2C%20in%20which%20Rft1,date%2C%20the%20identity%20of%20the')
  67. AnnotationURLCitation(end_index=21552, start_index=21375, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=identified%20Rft1%20by%20yeast%20genetics,vitro%20flipping%20assay%20using%20proteoliposomes')
  68. AnnotationURLCitation(end_index=21680, start_index=21553, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=match%20at%20L108%20flippase%20remains,Dol')
  69. AnnotationURLCitation(end_index=22023, start_index=21877, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11014557/#:~:text=is%20essential%20for%20the%20viability,termini%20facing%20the')
  70. AnnotationURLCitation(end_index=22171, start_index=22024, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11365447/#:~:text=including%20RFT1,a%20molecular%20characterization%20of%20human')
  71. AnnotationURLCitation(end_index=22648, start_index=22474, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=our%20results%20unequivocally%20support%20the,ER%20membrane%20during%20LLO%20biosynthesis')
  72. AnnotationURLCitation(end_index=23083, start_index=22968, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=complex,independent%20flippase')
  73. AnnotationURLCitation(end_index=23411, start_index=23296, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=complex,independent%20flippase')
  74. AnnotationURLCitation(end_index=23524, start_index=23412, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=f%29,independent%20flippase')
  75. AnnotationURLCitation(end_index=24080, start_index=23915, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=of%20M5GN2%20to%20M3GN2%20after,lipid%20bilayer%20of%20reconstituted%20liposomes')
  76. AnnotationURLCitation(end_index=24452, start_index=24287, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=of%20M5GN2%20to%20M3GN2%20after,lipid%20bilayer%20of%20reconstituted%20liposomes')
  77. AnnotationURLCitation(end_index=24847, start_index=24682, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=of%20M5GN2%20to%20M3GN2%20after,lipid%20bilayer%20of%20reconstituted%20liposomes')
  78. AnnotationURLCitation(end_index=25205, start_index=25031, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=our%20results%20unequivocally%20support%20the,ER%20membrane%20during%20LLO%20biosynthesis')
  79. AnnotationURLCitation(end_index=25612, start_index=25483, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11365447/#:~:text=including%20RFT1,its%20N%20and%20C%20termini')
  80. AnnotationURLCitation(end_index=25773, start_index=25613, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11365447/#:~:text=Rft1%2C%20using%20yeast%20cells%20as,work%20on%20this%20enigmatic%20protein')
  81. AnnotationURLCitation(end_index=26100, start_index=25962, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11014557/#:~:text=plays%20in%20N,work%20on%20this%20enigmatic%20protein')
  82. AnnotationURLCitation(end_index=26432, start_index=26272, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11014557/#:~:text=Both%20the%20AlphaFold2%20model%20and,MurJ%20lipid%20II%20flippases%20which')
  83. AnnotationURLCitation(end_index=26572, start_index=26433, title='Molecular characterization of Rft1, an ER membrane protein associated with congenital disorder of glycosylation RFT1-CDG - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11014557/#:~:text=match%20at%20L595%20potenqal%20%2858%E2%80%9361%29,Fig')
  84. AnnotationURLCitation(end_index=27046, start_index=26907, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=Dol,vitro%20flipping%20assay%20using%20proteoliposomes')
  85. AnnotationURLCitation(end_index=27162, start_index=27047, title='Rft1 catalyzes lipid-linked oligosaccharide translocation across the ER membrane - PMC', type='url_citation', url='https://pmc.ncbi.nlm.nih.gov/articles/PMC11182771/#:~:text=complex,independent%20flippase')
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