Chap98 PSA

  1. Human kallikrein gene map?
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  2. Short note on PSA.
    • PSA is a glycoprotein acting as a serineprotease of molecular weight 33 kD that contains 7% carbohydrate. 
    • Biologic role of PSA - lyse the clot in the ejaculate, but it is at present unknown why this clotting and lysing mechanism is important to reproductive physiology.
    • PSA is an organ-specific but not a cancer specific marker. 
    • Pre-pro-PSA (261 aminoacids) is processed in the endoplasmic reticulum of prostatic epithelial cells, where a 17-peptide pre-region residue is cleaved.  Seven more peptides are then cleaved from the propeptide to form the active PSA peptide
  3. Different molecular forms of PSA?
    • Free (unbound)
    • Complexed (bound)

    • Complexed PSA bound with 
    • -  α1-antichymotrypsin (ACT), an endogenous serine protease inhibitor. This form of complexed PSA (PSA-ACT) is enzymatically inactive yet has immunoreactivity.
    • - α2-macroglobulin (PSA-A2M).

    Free PSA, found in lower concentrations than complexed PSA (PSA-ACT), is also enzymatically inactive, yet it is also immunoreactive, whereas PSA-A2M is not.

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  4. Function of spermoglein?
    Capacitation - a series of changes in cell membranes, enzyme activities, and ion fluxes that sperm undergo as they traverse the female urogenital tract to reach the zona pellucida and fertilize the egg
  5. Prostatic Acid Phosphatase?
    Acid phosphatase activity is more than 200 times more abundant in prostate tissue than in any other tissue and is the source of the high levels of acid phosphatase in ejaculate.
  6. Role of %PSA?
    The role for % fPSA is more applicable to PSA levels less than 10 ng/mL because the positive predictive rate of total PSA greater than 10 to 20 ng/mL has been demonstrated to be as high as 80%.
Card Set
Chap98 PSA