ADAM7

ADAM metallopeptidase domain 7
Identifiers
SymbolsADAM7 ; ADAM 7; ADAM-7; EAPI; GP-83; GP83
External IDsOMIM: 607310 HomoloGene: 2830 IUPHAR: 1655 GeneCards: ADAM7 Gene
Orthologs
SpeciesHumanMouse
Entrez875611500
EnsemblENSG00000069206ENSMUSG00000022056
UniProtQ9H2U9O35227
RefSeq (mRNA)NM_003817NM_007402
RefSeq (protein)NP_003808NP_031428
Location (UCSC)Chr 8:
24.44 – 24.53 Mb		Chr 14:
68.5 – 68.53 Mb
PubMed search


Disintegrin and metalloproteinase domain-containing protein 7 is a protein that in humans is encoded by the ADAM7 gene.[1] ADAM7 is an 85-kDa enzyme that is a member of the transmembrane ADAM (A Disintegrin and Metalloprotease) protein family. It is important for the maturation of sperm cells in mammals. ADAM7 is also denoted as: ADAM_7, ADAM-7, EAPI, GP-83, and GP83.

Function

The functions of ADAM7 directly relate to sperm maturation and fertilization. Sperm are immobile until traversing the epididymis, in which the sperm interact with many proteins secreted by epihtelial cells of the epididymis. [2]Lacking protease activity, ADAM7 may play roles in protein-protein interactions and cell adhesion processes including sperm-egg fusion. ADAM7 is secreted by epidermis cells and transferred to the maturing sperm's surface. As determined through mouse gene knock-out studies, the amount of ADAM7 secreted is directly linked to ADAM2 and ADAM3 protein levels. [3] Complex formation between ADAM7, Calnexin, Hspa5, and Itm2b have been shown to act as a molecular chaperone. Furthermore, complex formation with Itm2b is increased during sperm capacitation leading to a conformation change in ADAM7.[3] Mutations in this gene may be involved in the progression of melanoma.

Mechanism of Secretion and Membrane Transfer

ADAM7 is synthesized in epididymis cells and transferred to the membrane of immature sperm cells as they traverse the epididymis during ejaculation. Epithelial cells of the epididymis incorporate ADAM7 into their membrane normally like other integral membrane protein.[2] Portions of the membrane are secreted as exosome vesicles. Secretion in this manner is an apocrine secretion in which apical blebs containing a portion of the epididymis cell are released from the cell. The apical blebs then encounter the immature sperm cell membrane within the convoluted tubules of the epididymis. The apical bleb and immature sperm cell membrane then fuse, ultimately incorporating ADAM7 into the sperm cell membrane.[4][5]

Physical characteristics

Human ADAM7 contains a sequence of 756 amino acids.[6] Numerous mammalian orthologs are currently known.[7] The largest portion of ADAM7 resides in the extracellular space. A short helical trasnmembrane sequence anchors the sequence while a short cytoplasmic sequence exists. This is consistant with its secretory functions. [8]

Localization

ADAM7 expression is localized in mammalian epididymis cells. Expression of ADAM7 is higher in the caput epididymis and decreases in cells towards the distal epididymis. [9] ADAM7 is also present in mature sperm cell membranes of mice.[10] Thus, ADAM7 is synthesized in the epididymus and transferred to the maturing sperm cell membrane.

Model Organisms

Due to the large mammalian homology, ADAM7 is primarily studied in Mus Musculus.

References

  1. ↑ "Entrez Gene: ADAM metallopeptidase domain 7".
  2. ↑ 2.0 2.1 Oh, Jeong Su; Han, Cecil; Cho, Chunghee (2009). "ADAM7 Is Associated with Epididymosomes and Integrated into Sperm Plasma Membrane". Molecules and Cells 28: 441–446. doi:10.1007/s10059-009-0140-x.
  3. ↑ 3.0 3.1 Cho C (Oct 2012). "Testicular and epididymal ADAMs: expression and function during fertilization". Nature Reviews. Urology 9 (10): 550–560. doi:10.1038/nrurol.2012.167. PMID 22926424.
  4. ↑ Hermo, L; Jacks, D (2002). "Nature’s ingenuity: bypassing the classical secretory route via apocrine secretion". Mol. Reprod. Dev 63: 394–410.
  5. ↑ Sullivan, R; Saez, F; Girouard, J; Frenette, G (2005). "Role of exosomes in sperm maturation during the transit along the male reproductive tract". Blood Cells Mol. Dis. 35: 1–10.
  6. ↑ "Homo sapiens (human): 8756". www.genome.jp. Retrieved 9 March 2015.
  7. ↑ "ORTHOLOGY: K16071". www.genome.jp. Retrieved 9 March 2015.
  8. ↑ "Disintegrin and Metalloproteinase Domain-containing Protein 7.". UniProt. Retrieved 29 April 2015.
  9. ↑ Oh J, Woo JM, Choi E, Kim T, Cho BN, Park ZY et al. (Jun 2005). "Molecular, biochemical, and cellular characterization of epididymal ADAMs, ADAM7 and ADAM28". Biochemical and Biophysical Research Communications 331 (4): 1374–1383. doi:10.1016/j.bbrc.2005.04.067. PMID 15883027.
  10. ↑ Kim T, Oh J, Woo JM, Choi E, Im SH, Yoo YJ et al. (Apr 2006). "Expression and relationship of male reproductive ADAMs in mouse" (PDF). Biology of Reproduction 74 (4): 744–750. doi:10.1095/biolreprod.105.048892. PMID 16407499.

External links


Category:Peptidase

Category:Human proteins