Elucidating the role of TM9SF2 in membrane trafficking
type: CreativeWork
description: New proteins and lipids are modified by the Golgi apparatus (Golgi) before being sorted for transport to their final destinations. The Golgi comprises sequential membrane-bound, motile compartments called cisternae. The most prominent Golgi modification is glycosylation, the addition of glycans by a group of enzymes called glycosyltransferases. Glycosylation has no template; therefore, it relies on the sequential organisation of glycosyltransferases within the Golgi. The cisternal maturation model proposes that cisternae progress through the Golgi, acquiring the necessary components as required. In theory, this would lead to resident Golgi enzymes becoming mislocalised. One mechanism to prevent enzyme mislocalisation is their capture by vesicles formed by coat protein complex 1 (COP1), via cargo adaptors such as Golgi phosphoprotein 3 (GOLPH3), for recycling to earlier parts of the Golgi. Published genome-wide CRISPR-Cas9 knockout screens interrogating glycosylation pathways have implicated the highly conserved Transmembrane Nine Superfamily Member 2 (TM9SF2) as a potential novel cargo adaptor. Additional evidence supporting this role comes from the observations that loss of TM9SF2 influences the cellular localisation and/or stability of some glycosyltransferases, and that orthologues possess a COPI binding motif. Taking an explorative approach, we generated knockout cell lines for all four members of the human TM9SF family and used assays including flow cytometry, immunofluorescence, immunoblotting, and biochemistry, to reveal novel glycosylation and morphological phenotypes, as well as new interactors. We provide evidence to confirm the cytosolic protein, Synapse-associated protein 1 (SYAP1), is a binding partner of TM9SF2, and hypothesise it may play a role in functional regulation. In addition, we identify two novel TM9SF2 cargo proteins, the enzymes, β-1,4- galactosyltransferase 1 (B4GALT1) and Sulfhydryl oxidase 2 (QSOX2). We show that two residues within the …
abstract: New proteins and lipids are modified by the Golgi apparatus (Golgi) before being sorted for transport to their final destinations. The Golgi comprises sequential membrane-bound, motile compartments called cisternae. The most prominent Golgi modification is glycosylation, the addition of glycans by a group of enzymes called glycosyltransferases. Glycosylation has no template; therefore, it relies on the sequential organisation of glycosyltransferases within the Golgi. The cisternal maturation model proposes that cisternae progress through the Golgi, acquiring the necessary components as required. In theory, this would lead to resident Golgi enzymes becoming mislocalised. One mechanism to prevent enzyme mislocalisation is their capture by vesicles formed by coat protein complex 1 (COP1), via cargo adaptors such as Golgi phosphoprotein 3 (GOLPH3), for recycling to earlier parts of the Golgi. Published genome-wide CRISPR-Cas9 knockout screens interrogating glycosylation pathways have implicated the highly conserved Transmembrane Nine Superfamily Member 2 (TM9SF2) as a potential novel cargo adaptor. Additional evidence supporting this role comes from the observations that loss of TM9SF2 influences the cellular localisation and/or stability of some glycosyltransferases, and that orthologues possess a COPI binding motif. Taking an explorative approach, we generated knockout cell lines for all four members of the human TM9SF family and used assays including flow cytometry, immunofluorescence, immunoblotting, and biochemistry, to reveal novel glycosylation and morphological phenotypes, as well as new interactors. We provide evidence to confirm the cytosolic protein, Synapse-associated protein 1 (SYAP1), is a binding partner of TM9SF2, and hypothesise it may play a role in functional regulation. In addition, we identify two novel TM9SF2 cargo proteins, the enzymes, β-1,4- galactosyltransferase 1 (B4GALT1) and Sulfhydryl oxidase 2 (QSOX2). We show that two residues within the …
author: Brown, Katherine
language: eng
keywords: Golgi, Golgi apparatus, Membrane Trafficking, Golgi enzymes, Golgi enzyme retention, Adaptor protein
license: https://www.repository.cam.ac.uk/bitstreams/4beb5ae7-3999-4201-8fa7-031409d25329/download
license: http://purl.org/NET/rdflicense/allrightsreserved
date published: 2025-07-04
date modified: 2026-07-22T22:23:59Z
provider: Cambridge University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Cambridge

PropertyValue
property ID: DOI
value: 10.17863/CAM.123747