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, respon ...

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 b ...

Function

The heterotetrameric adaptor protein (AP) complexes

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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. T ...

), 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.

Function

Clinical relevance

See also

References

External links

Further reading