COG4 Gene
The COG4 gene encodes a protein essential for Golgi function; mutations can lead to Saul‑Wilson syndrome or COG4‑congenital disorder of glycosylation.
Overview
The COG4 gene provides instructions for making a protein called component of oligomeric Golgi complex 4 (COG4). COG4 is one piece of the conserved oligomeric Golgi (COG) complex, which maintains normal functions in the Golgi apparatus—a cell structure where newly produced proteins are modified, such as by glycosylation, to carry out their functions.
The COG complex plays an important role in retrograde transport, moving proteins from the Golgi apparatus back to the endoplasmic reticulum (ER). This pathway is crucial for recycling unneeded proteins and relocating misplaced proteins within the cell. COG4 helps tether vesicles to the Golgi membrane, preparing them for transport to the ER.
Health Conditions Related to Genetic Changes
Saul‑Wilson Syndrome
At least two mutations in the COG4 gene cause Saul‑Wilson syndrome, a condition characterized by short stature (dwarfism) and other skeletal abnormalities. The mutations change a single nucleotide in the gene, resulting in the same amino‑acid substitution in the protein: glycine is replaced by arginine at position 516 (Gly516Arg or G516R). This change alters the protein’s structure but still allows it to join the COG complex. The abnormal COG4 increases retrograde transport between the Golgi and ER—a gain‑of‑function effect. The mechanism by which increased transport impairs bone growth remains unclear.
COG4‑Congenital Disorder of Glycosylation (COG4‑CDG)
Other mutations in the COG4 gene cause COG4‑CDG, which often leads to developmental delay, intellectual disability, seizures, and microcephaly. These mutations reduce or eliminate COG4 protein, impairing COG complex formation and Golgi function. A dysfunctional Golgi apparatus results in abnormal protein glycosylation, affecting multiple body systems.
Other Names for This Gene
- COD1
- COD1, S. CEREVISIAE, HOMOLOG OF
- COG4 gene
Additional Information & Resources
Genomic Location
The COG4 gene is located on chromosome 16.
References
- Blackburn JB, D'Souza Z, Lupashin VV. Maintaining order: COG complex controls Golgi trafficking, processing, and sorting. FEBS Lett. 2019 Sep;593(17):2466-2487.
- Ferreira C. Saul-Wilson Syndrome. 2020 Feb 20. In: GeneReviews.
- Ferreira CR, et al. A Recurrent De Novo Heterozygous COG4 Substitution Leads to Saul-Wilson Syndrome, Disrupted Vesicular Trafficking, and Altered Proteoglycan Glycosylation. Am J Hum Genet. 2018 Oct 4;103(4):553-567.
- Ferreira CR, et al. Defining the clinical phenotype of Saul-Wilson syndrome. Genet Med. 2020 May;22(5):857-866.
- Reynders E, et al. Golgi function and dysfunction in the first COG4-deficient CDG type II patient. Hum Mol Genet. 2009 Sep 1;18(17):3244-56.
- Richardson BC, et al. Structural basis for a human glycosylation disorder caused by mutation of the COG4 gene. Proc Natl Acad Sci U S A. 2009 Aug 11;106(32):13329-34.