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37 Cards in this Set
- Front
- Back
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What type of hormone is cholesterol used to produce?
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Steroid Hormones
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What functions do steroid and thyroid hormones have?
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-Cell growth and differntiation
-Metabolism -Development |
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Where are steroid and thyroid hormones mostly produced?
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-Hypothalamus
-Thyroid -Gonads |
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What is the general signalling path of steroid/thyroid hormones?
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1) Start with sensory inpt from the environment
2)This signals CNS which in turns signals hypothalamus 3)Hypothalamus produces hypothalamic hormones which signal the anterior pituitary 4)Anterior pituitary makes many dif hormones that signal all the majjor glands, which will produce T3/T4 and steroid hormones |
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What are the propertes of steroid hormones?
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-Hydrophobic and insoluble .: need a ptn carrier
-Produced in endocrine glands (gonads and adrenals) -Main effect: Coordinate behavioural and physiological responses for specific biolgical responses (ex: reproducton) |
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What type of hormones do the adrenal glands produce?
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Mineralocorticoids
Glucocorticoids |
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What type of hormones do the gonads produce?
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Sex hormones (testosterone, aldosterone....)
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What is te pathway to make steroid hormones?
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1) Cholesterol
2) Pregnenolene 3) Progesterone 4) Cortisol, Corticosterone, Testosterone 5) Corticosterone->aldosterone Testosterone -> Estadiol |
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What kind of hormone is cortisol? What does it do?
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-Glucocorticoid
-Affects ptn and carbohydrate metabolism -suppresses immune response, inflammation and allergic responses |
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What kind of hormone is aldosterone? What does it affect?
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--Mineralocorticoid
-Regulates absorption of water and ions in the kidney |
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What type of hormone is estradiol? What does it affect?
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-Sex hormone
-Influences 2ry sex characterisitics -Regulates female reproductive cycle |
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How do steroid hormones enter the cell?
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Simple diffusion (they do NOT have a receptor at PM, like the other horones do)
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What type of receptors do steroid hormones bind?
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Nuclear receptors (inside the cell)
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What are Hormone Response Elements?
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Highly specific DNA seq in target genes that are bound by steroid-receptor complex
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What does the steroid hormone receptor look like?
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N-term---Transcription Act----DNA Binding Domain-----Hormone Binding Domain---C-term
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What is the hormone binding domain?
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Hormon binds directly here on the receptor
(Each receptor will have its own HBD, specific) |
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What is the DNA binding domain?
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Domain that will bind to HREs (specific DNA seq on target cells, that are usually in the promoter region)
-Forms 2 zinc fingers -DBD is exposed after the steroid has bound the hormone |
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What is the transcrition activation domain?
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Recruits RNA Pol II to activate transcription of the target gene
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What happens whena steroid hormone binds its receptor?
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-Complex dimerizes
-both tog are important to bind DNA (i.e. HRE binds to both DBD at the same time) |
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What do the zinc fingers recognize when the hormone receptor complex binds the DNA?
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They each recognize a specific 6-nucleotide region on the HRE
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What happens to the steroid hrmone eceptors on the absence of the hormone?
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Steroid hormone receptors are usually in the cytoplasm and are ass't w/ HSP and are P
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What is the mechanism of steroid hormone action?
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1) Hormones passively diffuse into the cell.
2)Receptor is usually in the cytoplasm and needs to get to the nucleus (.: has an NLS, that is covered by HSP90) 3)Steroid hormone competes fo receptor interaction with HSP90 4)When hormone binds receptor, conform change, kicks off HSP 90: -Get dimerization -Exposes NLS: can be taken to nucleus and bind the HRE and induce transcription |
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What do thyroid hormones regulte?
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Metabolism and development
(they have pleiotropic effects: one hormone has many effects/phenotypes) |
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How are thyroid hormones produced?
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-Pituitary gland signal thyroid gland by secreting TSH (thyroid stimulating hormone)
-Thyroid then secretes TH (thyroid hormone: T3 or T4) |
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What type of hormones are T3 and T4?
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They are protein derivatives (come from tyrosine)
However they behave like steroid hormones cuz tyrosine is ~hydrophobic and modified and they are water insoluble |
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How are T3 and T4 made?
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Made from Thyroglobulin protein, which is stored then iodinated and proteolyzed to produce T3 and T4
The thyroid hormones are formed when 2 iodinated- tyrosines on thyroglobulin are oxidatively coupled |
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How many times is T3 iodinated? T4?
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T3: 3 times
T4: 4 times |
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What are the portein carriers for T3 and T4?
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-Thyroxine binding protein
-Prealbumin -Albumin |
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Which is the more active form of the thyroid hormone? Which is more prevalent when synthesized from the thyroid?
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-T3 is more active
-T4 is synthesized more by follicular cells |
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What do thyroid hormones bind? Where?
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They bind thyroid hormone responsive elements (TRE) in the nucleus (like steroid hormone, they also diffuse through PM)
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How are thyroid hormone responsive genes (THRG)transactivated?
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1) T3 binds the thyroid hormone receptor (TR) (T4 can be converted to T3 when it reaches the target cell)
2) T3-TR binds TRE , which is in the promoter region of THRG |
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How are THRG's regulated?
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Through conf. change in the DNA structure, which allos RNA Pol to bind to THRG
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What main kinase controls the cell cycle in response to extracellular stimuli?
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CDK (cyclin dependent kinase)
CDK is active when it ass't with regulatory cyclin subunit |
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How many cyclins and CDKs do mammalian cells have?
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Cyclins: 10
CDKs: 8 |
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What do CDKs do?
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Signal various things that are required throughout the cell cycle
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How are CDK activities regulated?
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-Changes in the expression of certain genes
-deP/P of themselves -Proteolysis by the proteasome machinery |
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What are the steps involved in CDK regulation by P and proteolysis?
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1)No cyclin present, so CDK inactive
2)Cyclin synthesized and accumulates 3)Cyclin-Cdk form a complex, but Tyr15-P, .: complex inactive 4)Thr160 is P and Tyr15 is deP -> activation of cyclin-CDK 5)CDK P a phosphatase which activates more CDK 6) CDK P DBRP 7) DBRP triggers ubiquitin ligase to add ubiquitin to cyclin 8) Cyclin is degraded by the proteasome, leaving CDK inactive |
