The Golgi matrix is a collection of proteins involved in the structure and function of the

Golgi apparatus The Golgi apparatus (), also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic cells. Part of the endomembrane system in the cytoplasm, it packages proteins into membrane-bound vesicles ...

. The matrix was first isolated in 1994 as an amorphous collection of 12 proteins that remained associated together in the presence of

detergent A detergent is a surfactant or a mixture of surfactants with cleansing properties when in dilute solutions. There are a large variety of detergents, a common family being the alkylbenzene sulfonates, which are soap-like compounds that are m ...

(which removed Golgi membranes) and 150 m M

NaCl Sodium chloride , commonly known as salt (although sea salt also contains other chemical salts), is an ionic compound with the chemical formula NaCl, representing a 1:1 ratio of sodium and chloride ions. With molar masses of 22.99 and 35.45 g/ ...

(which removed weakly associated proteins). Treatment with a

protease A protease (also called a peptidase, proteinase, or proteolytic enzyme) is an enzyme that catalyzes (increases reaction rate or "speeds up") proteolysis, breaking down proteins into smaller polypeptides or single amino acids, and spurring the form ...

enzyme removed the matrix, which confirmed the importance of proteins for the matrix structure. Modern freeze etch

electron microscopy An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a ...

(EM) clearly shows a mesh connecting Golgi

cisternae A cisterna (plural cisternae) is a flattened membrane vesicle found in the endoplasmic reticulum and Golgi apparatus. Cisternae are an integral part of the packaging and modification processes of proteins occurring in the Golgi. Function Protein ...

and associated

vesicles Vesicle may refer to: ; In cellular biology or chemistry * Vesicle (biology and chemistry), a supramolecular assembly of lipid molecules, like a cell membrane * Synaptic vesicle ; In human embryology * Vesicle (embryology), bulge-like feature ...

. Further support for the existence of a matrix comes from EM images showing that ribosomes are excluded from regions between and near Golgi cisternae.Fig. 14 in GMAP210c

Structure and function

The first individual protein component of the matrix was identified in 1995 as Golgin A2 (then called GM130). Since then, many other golgin family proteins have been found to be in the Golgi matrix and are associated with the Golgi membranes in a variety of ways. For example, GMAP210 (Golgi Microtubule Associated Protein 210) has an

ALPS The Alps () ; german: Alpen ; it, Alpi ; rm, Alps ; sl, Alpe . are the highest and most extensive mountain range system that lies entirely in Europe, stretching approximately across seven Alpine countries (from west to east): France, ...

(Amphipathic Lipid-Packing Sensor) motif in the N-termal 38 amino acids and an

ARF1 ADP-ribosylation factor 1 is a protein that in humans is encoded by the ''ARF1'' gene. Function ADP-ribosylation factor 1 (ARF1) is a member of the human ARF gene family. The family members encode small guanine nucleotide-binding proteins tha ...

-binding domain called GRAB (Grip-Related Arf-Binding) at the C-terminus. Thus, the GRAB-domain can bind indirectly to Golgi cisternae and its ALPS motif can tether vesicles. Golgins have coiled-coil domains and are thus predicted to have elongated structures up to 200 nm in length. Most are

peripheral membrane proteins Peripheral membrane proteins, or extrinsic membrane proteins, are membrane proteins that adhere only temporarily to the biological membrane with which they are associated. These proteins attach to integral membrane proteins, or penetrate the periph ...

attached at one end to Golgi membranes. They have flexible regions between the coiled-coil domains, which make them ideal candidates for mediating the dynamic vesicle docking to Golgi cisternae and dynamic structure of the Golgi itself. Golgi reassembly-stacking proteins are an evolutionarily conserved family of proteins in the Golgi matrix.

GRASP65 Golgi reassembly-stacking protein of 65 kDa (GRASP65) also known as Golgi reassembly-stacking protein 1 (GORASP1) is a protein that in humans is encoded by the ''GORASP1'' gene. Function The Golgi complex plays a key role in the sorting and ...

and

GRASP55 Golgi reassembly-stacking protein of 55 k Da (GRASP55) also known as golgi reassembly-stacking protein 2 (GORASP2) is a protein that in humans is encoded by the ''GORASP2'' gene. It was identified by its homology with GRASP65 and the protein's a ...

are the 2 human GRASPs. These proteins were named from their requirement for accurate Golgi reassembly during an ''in vitro'' assay, but they have also been shown to function ''in vivo'', as shown in the accompanying figure. GRASPs associate with lipid bilayers because they are

myristoylated Myristoylation is a lipidation modification where a myristoyl group, derived from myristic acid, is covalently attached by an amide bond to the alpha-amino group of an N-terminal glycine residue. Myristic acid is a 14-carbon saturated fatty aci ...

and their

myristic acid Myristic acid (IUPAC name: tetradecanoic acid) is a common saturated fatty acid with the molecular formula CH3(CH2)12COOH. Its salts and esters are commonly referred to as myristates or tetradecanoates. It is named after the binomial name for nu ...

residue intercalates into the lipid layer. Their ''trans'' oligomerization is controlled by phosphorylation and is thought to explain the fragmentation of the Golgi as required during mitosis.

Components

* Bicaudal D homolog *

CASP Critical Assessment of Structure Prediction (CASP), sometimes called Critical Assessment of Protein Structure Prediction, is a community-wide, worldwide experiment for protein structure prediction taking place every two years since 1994. CASP prov ...

* CG-NAP *

COH1 Intermembrane lipid transfer protein VPS13B, also known as vacuolar protein sorting-associated 13B, and Cohen syndrome protein 1 is a protein that in humans is encoded by the ''VPS13B'' gene. It is a giant protein associated with the Golgi appa ...

* GCC88 * GCC185 * GCP60 *

Giantin Giantin or Golgin subfamily B member 1 is a protein that in humans is encoded by the ''GOLGB1'' gene. Giantin is located at the cis-medial rims of the Golgi apparatus and is part of the Golgi matrix that is responsible for membrane trafficking ...

* GMAP210 * Golgin A2 * Golgin A7 * Golgin 45 * Golgin 67 and the product of duplicated gene GOLGA8A * Golgin 84 * Golgin 97 * Golgin 160 * Golgin 245 * GORAB *

* JAKMIP2 * JAKMIP3 *

TMF1 TATA element modulatory factor is a protein that in humans is encoded by the ''TMF1'' gene. Interactions TMF1 has been shown to interact Advocates for Informed Choice, dba interACT or interACT Advocates for Intersex Youth, is a 501(c)(3) ...

USO1 General vesicular transport factor p115 is a protein that in humans is encoded by the ''USO1'' gene. Function The protein encoded by this gene is a peripheral membrane protein which recycles between the cytosol and the Golgi apparatus during i ...

Disease associations

*CG-NAP hereditary

Long QT syndrome Long QT syndrome (LQTS) is a condition affecting repolarization (relaxing) of the heart after a heartbeat, giving rise to an abnormally lengthy QT interval. It results in an increased risk of an irregular heartbeat which can result in fainting, ...

LQT11 *COH1

Cohen Syndrome Cohen syndrome (also known as Pepper syndrome or Cervenka syndrome) is a very rare autosomal recessive genetic disorder with varied expression, characterised by obesity, intellectual disability, distinct craniofacial abnormalities and potential oc ...

*GMAP210

Achondrogenesis Achondrogenesis is a number of disorders that are the most severe form of congenital chondrodysplasia (malformation of bones and cartilage). These conditions are characterized by a small body, short limbs, and other skeletal abnormalities. As a r ...

type IA *Golgin A2 a complex, neuromuscular disorder *GORAB Gerodermia osteodysplastica

References

{{reflist, 35em Cell anatomy Histology Matrices (biology) Organelles