AP-4 complex subunit sigma-1 is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...
that in humans is encoded by the ''AP4S1''
gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
.
Function
The
heterotetrameric
A tetrameric protein is a protein with a quaternary structure of four subunits (tetrameric). Homotetramers have four identical subunits (such as glutathione S-transferase), and heterotetramers are complexes of different subunits. A tetramer ...
adaptor protein (AP) complexes
sort
Sort may refer to:
* Sorting, any process of arranging items in sequence or in sets
** Sorting algorithm, any algorithm for arranging elements in lists
** Sort (Unix), a Unix utility which sorts the lines of a file
** Sort (C++), a function in the ...
integral membrane proteins at various stages of the endocytic and secretory pathways. AP4 is composed of 2 large chains, beta-4 (
AP4B1) and epsilon-4 (
AP4E1), a medium chain, mu-4 (
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 ...
), and a small chain, sigma-4 (AP4S1, this gene).
Clinical relevance
Deficiency of AP-4 leads to childhood-onset
hereditary spastic paraplegia
Hereditary spastic paraplegia (HSP) is a group of inherited diseases whose main feature is a progressive gait disorder. The disease presents with progressive stiffness (spasticity) and contraction in the lower limbs. HSP is also known as hereditar ...
and it is currently hypothesized that AP4-complex-mediated trafficking plays a crucial role in brain development and functioning.
See also
*
AP2 adaptor complex The AP2 adaptor complex is a multimeric protein that works on the cell membrane to internalize cargo in clathrin-mediated endocytosis. It is a stable complex of four adaptins which give rise to a structure that has a core domain and two appendage d ...
References
External links
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Further reading
*
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Proteins