DNA: Integration Flashcards
PTH is classified as a
Polypeptide
Regulates calcium homeostasis
Parathyroid hormone
The receptor of PTH is found in its target cell’s
Cell membrane
Solubility of PTH
Hydrophilic
Secondary messenger employed by PTH in order to bring about its effect
cAMP
It is secreted as a precursor hormone that is continuously degraded
PTH
Primary gene product of the parathyroid gland
PreproPTH
How many AA residues does PTH have
84
Immediate precursor of PTH
ProPTH
The leader of sequence, consisting of 25 AAs, is found in the
PreproPTH
Best describes the leader sequence
Hydrophobic
Characteristic of the pro sequence
Basic hexapeptide
Sequences of the PTH responsible for receptor binding
25-34
Enzyme responsible for cleaving PTH
Cathepsins
Most of the PTH is actually degraded in the
Parathyroid gland
What is the primary stimulus for the secretion of and activity of PTH
Low serum calcium levels
The single most finding in a person suffering from primary hyperpsrathyroidism
Hypercalcemia
In a person with primary hyperparathyroidism, what is the expected level of PTH
Increased
An overt sign of hyperparathyroidism
Nephrolithiasis
Medication that may bring about characteristic findings or mimic hyperparathyroidism
Thiazide diuretics
Polypeptide secreted as a precursor hormone and is cleaved by cathepsin. Binds to membrane receptors and activates adenylyl cyclase to produce cAMP.
PTH
S4 AA residues: biologically active
1-34
S4 AA residues: receptor binding PTH
25-34
S4 AA residues: C fragment sequence
37-84
PTH synthesis and secretion is regulated by
Serum ionized calcium concentrations
Is readily degraded inside the parathyroid glands
ProPTH
Rate of degradation is reduced if serum calcium levels is
Low
PTH is metabolized in
Liver
Manifestations of hyperparathyroidism
Mostly are asymptomatic, fatigue, malaise & serum hypercalcemia
Loss of bone mass. Often a laboratory diagnosis: xray, bone densitometry. Precursor of osteoporosis.
Osteopenia
Skeletal disorder characterized by low bone mass and microarchitectural disruption. Leads to skeletal fragility. Major risk factor for falls and fracture. Affects women more than men.
Osteoporosis
Risk factor for osteoporosis: being ______. In women, being ______. And in men, ________.
Women. Postmenopausal. Low testosterone levels.
Risk factor for osteoporosis: advanced ____. ________ ethnicity. Family history of ________. And _________ frame.
Age. Caucasian/asian. Osteoporosis. Thinness/small
Values: normal bone mineral density
> -1.0
Values: osteopenia
-1.0 to -2.5
Values: osteoporosis
< -2.5
Reduces bone resorption
Bisphosphonates (Alendronate)
Calcium lowering agent
Cinacalcet
