Clathrin adaptor proteins
Clathrin adaptor proteins, also known as adaptins, are vesicular transport adaptor proteins associated with clathrin. The association between adaptins and clathrin are important for vesicular protein targeting, cargo selection and transporting. Cl ...
, 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
AP-1 complex subunit mu-1 is a protein that in humans is encoded by the ''AP1M1'' gene.
Function
The protein encoded by this gene is the medium chain of the trans-Golgi network clathrin-associated protein complex AP-1. The other components of ...
**
AP1M2
**
AP1S1
**
AP1S2
*
AP1S3* complex 2
**
AP2A1
**
AP2A2
**
AP2B1
AP-2 complex subunit beta is a protein that in humans is encoded by the ''AP2B1'' gene.
Function
The protein encoded by this gene is one of two large chain components of the AP2 adaptor complex, which serves to link clathrin to receptors in c ...
**
AP2M1
AP-2 complex subunit mu is a protein that in humans is encoded by the ''AP2M1'' gene.
Function
This gene encodes a subunit of the heterotetrameric coat assembly protein complex 2 (AP2), which belongs to the adaptor complexes medium subunits f ...
**
AP2S1
* complex 3
**
AP3B1
AP-3 complex subunit beta-1 is a protein that in humans is encoded by the ''AP3B1'' gene.
Function
This gene encodes a protein that may play a role in organelle biogenesis associated with melanosomes, platelet dense granules, and lysosomes. Th ...
**
AP3B2
**
AP3D1
**
AP3M1
*
AP3M2**
AP3S1
**
AP3S2
* complex 4
**
AP4B1
AP-4 complex subunit beta-1 is a protein that in humans is encoded by the ''AP4B1'' gene.
Function
The heterotetrameric adaptor protein (AP) complexes sort integral membrane proteins at various stages of the endocytic and secretory pathways. A ...
**
AP4E1
AP-4 complex subunit epsilon-1 is a protein that in humans is encoded by the ''AP4E1'' gene.
Function
The heterotetrameric adaptor protein (AP) complexes sort integral membrane proteins at various stages of the endocytic and secretory pathway ...
**
AP4M1
AP-4 complex subunit mu-1 is a protein that in humans is encoded by the ''AP4M1'' gene.
Function
This gene encodes a subunit of the heterotetrameric AP-4 complex. The encoded protein belongs to the adaptor complexes medium subunits family. Thi ...
**
AP4S1
AP-4 complex subunit sigma-1 is a protein that in humans is encoded by the ''AP4S1'' gene.
Function
The heterotetrameric adaptor protein (AP) complexes sort integral membrane proteins at various stages of the endocytic and secretory pathways ...
* 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