Clathrin adaptor proteins, also known as adaptins, are proteins that mediate the formation of
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 a neuron, synaptic vesicles (or neurotransmitter vesicles) s ...
for intracellular trafficking and secretion. Adaptins are clustered subunits of adaptor protein (AP) complexes.
There are several types of adaptin, each related to a different AP complex.
Adaptins show
sequence similarity
Sequence homology is the biological homology between DNA, RNA, or protein sequences, defined in terms of shared ancestry in the evolutionary history of life. Two segments of DNA can have shared ancestry because of three phenomena: either a speci ...
to some
COPI
COPI is a coatomer, a protein complex that coats vesicle (biology), vesicles transporting proteins from the ''cis'' end of the Golgi complex back to the rough endoplasmic reticulum (ER), where they were originally Translation (genetics), synthesi ...
subunits, thus they are thought to have a common evolutionary origin.
The adaptin is a heterotetramer consisting of two large adaptins (beta and one other depending on the complex), a medium adaptin (mu), and a small adaptin (sigma):
* complex 1
**
AP1B1
**
AP1G1
AP-1 complex subunit gamma-1 is a protein that in humans is encoded by the ''AP1G1'' gene.
Function
Adaptins are important components of clathrin-coated vesicles transporting ligand-receptor complexes from the plasma membrane or from the tr ...
**
AP1G2
**
AP1M1
**
AP1M2
**
AP1S1
**
AP1S2
*
AP1S3* complex 2
**
AP2A1
**
AP2A2
**
AP2B1
**
AP2M1
**
AP2S1
* complex 3
**
AP3B1
**
AP3B2
**
AP3D1
**
AP3M1
*
AP3M2**
AP3S1
**
AP3S2
* complex 4
**
AP4B1
**
AP4E1
**
AP4M1
**
AP4S1
* complex 5
**
AP5Z1
**
AP5B1
**
AP5M1
**
AP5S1
A diagram of the 5 complexes is show
here
References
* Alberts, Johnson, Lewis, Raff, Roberts, Walter: ''Molecular Biology of the Cell'', 4th edition (2002), Garland Science.
*
Peripheral membrane proteins
{{Membrane-protein-stub