Prostasomes
Encyclopedia
Prostasomes were discovered in 1978 as submicrometre membranous vesicles
Vesicle (biology)
A vesicle is a bubble of liquid within another liquid, a supramolecular assembly made up of many different molecules. More technically, a vesicle is a small membrane-enclosed sack that can store or transport substances. Vesicles can form naturally because of the properties of lipid membranes , or...

 (40-500 nm in diameter) secreted by the prostate gland
Gland
A gland is an organ in an animal's body that synthesizes a substance for release of substances such as hormones or breast milk, often into the bloodstream or into cavities inside the body or its outer surface .- Types :...

 epithelial cells into seminal fluid. They possess an unusual lipid composition and a tight and highly-ordered structure of their lipoprotein
Lipoprotein
A lipoprotein is a biochemical assembly that contains both proteins and lipids water-bound to the proteins. Many enzymes, transporters, structural proteins, antigens, adhesins, and toxins are lipoproteins...

 membranes resembling lipid raft
Lipid raft
The plasma membrane of cells is made of a combination of glycosphingolipids and protein receptors organized in glycolipoprotein microdomains termed lipid rafts...

. The physiological role of prostasomes implicates improvement of sperm motility and protection against attacks from the female immune defense during the passage to the egg . Investigations have shown that cancerous prostate cells and prostate cells with low differentiation continue to produce and secrete prostasomes . The high incidence of prostate cancer
Prostate cancer
Prostate cancer is a form of cancer that develops in the prostate, a gland in the male reproductive system. Most prostate cancers are slow growing; however, there are cases of aggressive prostate cancers. The cancer cells may metastasize from the prostate to other parts of the body, particularly...

 in elderly men could take advantage of the immune protective activities supported by the prostasomes. Immune regulating proteins found in prostasomes include: amino-peptidase N (CD13); dipeptidyl-peptidase IV (CD26); enkephalinase (neutral endopeptidase, CD10); angiotensin converting enzyme (ACE, CD143); tissue factor TF (CD142, thromboplastin); decay accelerator factor (CD55); protectin (CD59
CD59
Protectin, a complement regulatory protein, also known as ', or MIRL is a human gene and protein....

, inhibitor of MAC) and complement regulatory membrane cofactor protein (CD46
CD46
CD46 complement regulatory protein also known as CD46 and Membrane Cofactor Protein is a protein which in humans is encoded by the CD46 gene. CD46 is an inhibitory complement receptor.- Gene :...

) . Prostasomes also contains high levels of divalent cations as: Zn2+, Ca2+ and Mg2+.
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