AP4E1

Adaptor-related protein complex 4, epsilon 1 subunit
Identifiers
Symbols	AP4E1 ; CPSQ4; SPG51
External IDs	OMIM: 607244 MGI: 1336993 HomoloGene: 22397 GeneCards: AP4E1 Gene
Gene ontology Molecular function • structural molecule activity Cellular component • coated pit • membrane coat • endosome lumen • trans-Golgi network membrane Biological process • intracellular protein transport • post-Golgi vesicle-mediated transport • membrane organization Sources: Amigo / QuickGO
Orthologs
Species	Human	Mouse
Entrez	23431	108011
Ensembl	ENSG00000081014	ENSMUSG00000001998
UniProt	Q9UPM8	Q80V94
RefSeq (mRNA)	NM_001252127	NM_175550
RefSeq (protein)	NP_001239056	NP_780759
Location (UCSC)	Chr 15: 50.91 – 51.01 Mb	Chr 2: 127.01 – 127.07 Mb
PubMed search

AP-4 complex subunit epsilon-1 is a protein that in humans is encoded by the AP4E1 gene.^[1]

Function

The heterotetrameric adaptor protein (AP) complexes sort 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; this gene), a medium chain, mu-4 (AP4M1), and a small chain, sigma-4 (AP4S1).^[1]

Clinical relevance

It is currently hypothesized that AP4-complex-mediated trafficking plays a crucial role in brain development and functioning.^[2]

Model organisms

Ap4e1 knockout mouse phenotype

Characteristic	Phenotype
Homozygote viability	Normal
Fertility	Normal
Body weight	Normal
Anxiety	Abnormal[3]
Neurological assessment	Normal
Grip strength	Normal
Hot plate	Normal
Dysmorphology	Normal
Indirect calorimetry	Normal
Glucose tolerance test	Normal
Auditory brainstem response	Normal
DEXA	Normal
Radiography	Normal
Body temperature	Normal
Eye morphology	Normal
Clinical chemistry	Abnormal[4]
Haematology	Abnormal[5]
Peripheral blood lymphocytes	Normal
Micronucleus test	Normal
Heart weight	Normal
Brain histopathology	Abnormal
Eye Histopathology	Normal
Salmonella infection	Normal[6]
Citrobacter infection	Normal[7]
All tests and analysis from[8][9]

Model organisms have been used in the study of AP4E1 function. A conditional knockout mouse line, called Ap4e1^{tm1a(KOMP)Wtsi[10][11]} was generated as part of the International Knockout Mouse Consortium program — a high-throughput mutagenesis project to generate and distribute animal models of disease to interested scientists.^[12][13][14]

Male and female animals underwent a standardized phenotypic screen to determine the effects of deletion.^[8][15] Twenty four tests were carried out on homozygous mutant mice and four significant abnormalities were observed.^[8] Females displayed decreased vertical activity in an open field test, had an abnormal complete blood count, hypoferremia, and a decreased corpus callosum size and enlarged lateral ventricles.^[8]

References

1. "Entrez Gene: adaptor-related protein complex 4".
2. Abou Jamra R, Philippe O, Raas-Rothschild A, Eck SH, Graf E, Buchert R, Borck G, Ekici A, Brockschmidt FF, N?then MM, Munnich A, Strom TM, Reis A, Colleaux L (May 2011). "Adaptor Protein Complex 4 Deficiency Causes Severe Autosomal-Recessive Intellectual Disability, Progressive Spastic Paraplegia, Shy Character, and Short Stature". Am J Hum Genet 88 (6): 788–95. doi:10.1016/j.ajhg.2011.04.019. PMC 3113253. PMID 21620353.
3. "Anxiety data for Ap4e1". Wellcome Trust Sanger Institute.
4. "Clinical chemistry data for Ap4e1". Wellcome Trust Sanger Institute.
5. "Haematology data for Ap4e1". Wellcome Trust Sanger Institute.
6. "Salmonella infection data for Ap4e1". Wellcome Trust Sanger Institute.
7. "Citrobacter infection data for Ap4e1". Wellcome Trust Sanger Institute.
8. Gerdin AK (2010). "The Sanger Mouse Genetics Programme: High throughput characterisation of knockout mice". Acta Ophthalmologica 88: 925–7. doi:10.1111/j.1755-3768.2010.4142.x.
9. Mouse Resources Portal, Wellcome Trust Sanger Institute.
10. "International Knockout Mouse Consortium".
11. "Mouse Genome Informatics".
12. Skarnes, W. C.; Rosen, B.; West, A. P.; Koutsourakis, M.; Bushell, W.; Iyer, V.; Mujica, A. O.; Thomas, M.; Harrow, J.; Cox, T.; Jackson, D.; Severin, J.; Biggs, P.; Fu, J.; Nefedov, M.; De Jong, P. J.; Stewart, A. F.; Bradley, A. (2011). "A conditional knockout resource for the genome-wide study of mouse gene function". Nature 474 (7351): 337–342. doi:10.1038/nature10163. PMC 3572410. PMID 21677750.
13. Dolgin E (2011). "Mouse library set to be knockout". Nature 474 (7351): 262–3. doi:10.1038/474262a. PMID 21677718.
14. Collins FS, Rossant J, Wurst W (2007). "A Mouse for All Reasons". Cell 128 (1): 9–13. doi:10.1016/j.cell.2006.12.018. PMID 17218247.
15. van der Weyden L, White JK, Adams DJ, Logan DW (2011). "The mouse genetics toolkit: revealing function and mechanism.". Genome Biol 12 (6): 224. doi:10.1186/gb-2011-12-6-224. PMC 3218837. PMID 21722353.

Further reading

• Dell'Angelica EC, Mullins C, Bonifacino JS (1999). "AP-4, a novel protein complex related to clathrin adaptors.". J. Biol. Chem. 274 (11): 7278–85. doi:10.1074/jbc.274.11.7278. PMID 10066790.
• Hirst J, Bright NA, Rous B, Robinson MS (1999). "Characterization of a fourth adaptor-related protein complex.". Mol. Biol. Cell 10 (8): 2787–802. doi:10.1091/mbc.10.8.2787. PMC 25515. PMID 10436028.
• Takatsu H, Futatsumori M, Yoshino K; et al. (2001). "Similar subunit interactions contribute to assembly of clathrin adaptor complexes and COPI complex: analysis using yeast three-hybrid system.". Biochem. Biophys. Res. Commun. 284 (4): 1083–9. doi:10.1006/bbrc.2001.5081. PMID 11409905.
• Boehm M, Aguilar RC, Bonifacino JS (2001). "Functional and physical interactions of the adaptor protein complex AP-4 with ADP-ribosylation factors (ARFs).". EMBO J. 20 (22): 6265–76. doi:10.1093/emboj/20.22.6265. PMC 125733. PMID 11707398.