Steroid hormone membrane receptor

One major use of the potential energy created by separating protons from electrons across membranes is to drive the synthesis of ATP. ATP then powers other metabolic processes, such as the formation of glucose (the major product of photosynthesis), or the transport of solutes discussed in the preceding section. In addition, the membrane potential can itself be directly coupled to pumping certain solutes against their concentration gradient (active transport). In those cases, the downhill diffusion of protons across the membrane provides the energy to pump other solutes uphill. (Picture a paddle wheel that taps a mountain stream for energy to grind grain.) Such membrane potentials also propel bacterial swimming by powering the rotation of their propellerlike flagella. Membrane potential energy is thus a currency as universal as ATP or glucose.

Cells of the zona fasciculata and zona reticularis lack aldosterone synthase (CYP11B2) that converts corticosterone to aldosterone, and thus these tissues produce only the weak mineralocorticoid corticosterone. However, both these zones do contain the CYP17A1 missing in zona glomerulosa and thus produce the major glucocorticoid, cortisol. Zona fasciculata and zona reticularis cells also contain CYP17A1, whose 17,20-lyase activity is responsible for producing the androgens, dehydroepiandosterone (DHEA) and androstenedione. Thus, fasciculata and reticularis cells can make corticosteroids and the adrenal androgens, but not aldosterone.

The most commonly used AAS in medicine are testosterone and its various esters (but most commonly testosterone undecanoate , testosterone enanthate , testosterone cypionate , and testosterone propionate ), [53] nandrolone esters (most commonly nandrolone decanoate and nandrolone phenylpropionate ), stanozolol , and metandienone (methandrostenolone). [1] Others also available and used commonly but to a lesser extent include methyltestosterone , oxandrolone , mesterolone , and oxymetholone , as well as drostanolone propionate , metenolone (methylandrostenolone), and fluoxymesterone . [1] Dihydrotestosterone (DHT; androstanolone, stanolone) and its esters are also notable, although they are not widely used in medicine. [54] Boldenone undecylenate and trenbolone acetate are used in veterinary medicine . [1]

where k b is the Boltzmann constant, T is the absolute temperature, and D is the diffusion coefficient of a steroid hormone in a uniform medium ( Schulten et al., 1981 ; Wilson and Pohorille, 1996 ). F 1 and F 2 are the force constants (., the second derivatives of the free energy as a function of the steroid-hexane distance, h ) in the orientations separated by the free-energy barriers ( Kessel et al., 2001b ). The value ΔΔ G is the difference in the solvation free energy of the system ( Eq. 1 ) above the barrier (Δ G a ) and below it (Δ G b ):

Steroid hormone membrane receptor

steroid hormone membrane receptor

where k b is the Boltzmann constant, T is the absolute temperature, and D is the diffusion coefficient of a steroid hormone in a uniform medium ( Schulten et al., 1981 ; Wilson and Pohorille, 1996 ). F 1 and F 2 are the force constants (., the second derivatives of the free energy as a function of the steroid-hexane distance, h ) in the orientations separated by the free-energy barriers ( Kessel et al., 2001b ). The value ΔΔ G is the difference in the solvation free energy of the system ( Eq. 1 ) above the barrier (Δ G a ) and below it (Δ G b ):

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