Hormone receptor proteins

An NIH Consensus Development Conference Statement22 advises that adjuvant hormonal therapy should be recommended to women whose tumors contain hormone-receptor protein regardless of age, menopausal status, involvement of axillary lymph nodes, or tumor size. They also support a benefit of adjuvant chemotherapy for most women with lymph node metastases or with primary breast cancers larger than 1 cm in diameter (both node-negative and node-positive).22... 

Elias JM, Margiotta M. Low temperature antigen restoration of steroid hormone receptor proteins in routine paraffin sections. I. Histotechnol. 1997 20 155-158. 

Affinity chromatography can be applied to the isolation and purification of virtually all biological macromolecules. It has been used to purify nucleic acids, enzymes, transport proteins, antibodies, hormone receptor proteins, drug-binding proteins, neurotransmitter proteins, and many others. 

Why are all known hormone receptors proteins Can other macromolecules serve as receptors ... 

With the availability of labeled hormones of high specific activity and the application of the principles of affinity chromatography, researchers were able to isolate cellular proteins that bind to plant hormones in vitro. Such proteins have been referred to as receptor proteins, binding proteins, or acceptor proteins. Tacit in the concept of hormone receptor proteins is the stereo-specific interaction of the hormone and the receptor protein (19). The resulting hormone-protein complex participates in growth processes that depend on new or enhanced protein synthesis. Advances in molecular biology and related sciences have enabled many researchers to study the role of receptors in the control of nuclear functions or other activities and to determine the site of primary hormonal action. 

Matthyssee and Phillips (20) isolated two nuclear proteins, from tobacco cells, that bound specifically to 2,4-D. Receptor proteins for auxins, kinetins, and GA have been found (21). Sub-cellular fractions from bean leaves were recently shown to bind abscisic acid (22). Preliminary experiments (22) indicated that maximum ABA binding activity coincides with the activities of membrane-bound Mg -dependent, K+-stimulated ATPase and glucan synthetase. Table I of Biswas and Roy (21) lists hormone receptor proteins reported in plant tissue. For a protein to qualify as a receptor molecule, it should have a high stereo-specific binding capacity (Kd 10 6 to 10 SM) for its particular hormone. In com coleoptiles, both IAA and NAA are equally effective in inducing cell elongations fractions of plasma membrane and endoplasmic reticular membrane contain receptor proteins with Kd values of 10 M to 10 M for auxins (5, 18). When one considers procedural... 

The C4 zinc finger is also found in a number of transcription factors, including steroid hormone receptor proteins. This motif forms a similar structure to that of C2H2 zinc finger but has four cysteines co-ordinated to the zinc ion instead of two cysteines and two histidines (see Fig. 4c). 

Jn Figure 2.1U, examine the order of ainiriD adds at the C termiivi of gastrin and cholecystokin. How many amino acids are identical in the two hormones Are any other identical sequences shared by these hormones Ihcsc questions are relevant lo the concept that a number of hormones with different functions are actually part of the same family of hormones. A number of proteins, such as various enzymes, hormone receptor proteins, and DNA-binding protcirLS, also share similar primary sequences and thus may becortsidered members of specific families of proteins. 

A variety of symptoms, not mentioned earlier, have also been associated with zinc deficiency. Zinc deficiency is thought to delay woxmd healing, impair the senses of taste and smell, and impair the functions of the immune system. (The impaired sense of taste is called hypogettsia.) Severe zinc deficiency results in impairment of the immune system and increased infections. These problems have been found in the severe deficiencies that occur in starvation (marasmus) and acrodermatitis enteropathica and in studies with animals. The immune system involves a large array of hormones, hormone receptor proteins, signaling proteins, and DNA-binding proteins, some of which require zinc for activity. It is not clear which of these components is most sensitive to zinc deficiency. 

Using formalin fixed tissues (8-72 hours) and appropriate positive and negative controis, the test for the presence of these hormone receptor proteins is performed by the immunoperoxidase method. A positive ER or PR tumor shows 1 % nuciear immunostaining and the semiquantitation immunostaining raw data are indicated beiow. 

Atypical mammalian cell contains up to 10,000 different kinds of proteins a yeast cell, about 5000. The vast majority of these proteins are synthesized by cytosolic ribosomes, and many remain within the cytosol. However, as many as half the different kinds of proteins produced in a typical cell are delivered to a particular cell membrane, an aqueous compartment other than the cytosol, or to the cell surface for secretion. For example, many hormone receptor proteins and transporter proteins must be delivered to the plasma membrane, some water-soluble enzymes such as RNA and DNA polymerases must be targeted to the nucleus, and components of the extracellular matrix as well as polypeptide signaling molecules must be directed to the cell surface for secretion from the cell. These and all the other proteins produced by a cell must reach their correct locations for the cell to function properly. 

Despite the fact that they can be much more reactive than nitrenes, carbene derivatives are less frequently cited in reports on photoaffinity labels. Two such derivatives of thyroid hormone have been described in which the amino group of the alanine side chain of 3,5,3 -triiodo-L-thyronine or 3,5,3, 5 -tetraiodo-L-thyronine was derivatized with 2-diazo-3,3,3-trifluoropropionate (246). Irradiation at 254 nm of these compounds with several cell lines yielded low incorporation of reagent (0.5-13.5%) into two forms of thyroid hormone receptor proteins. Low incorporation was also characteristic of early reports of photoaffinity labeling (e.g., 247) in which 0 -ethyl-2-diazomalonyl-cAMP and A, C)2. (ji(ethyl-2-diazomalonyl)-cAMP were used to generate carbenes which modify rabbit muscle phosphofructokinase. Similarly, only 3-14% of the potential sites of lactate dehydrogenase were labeled by the carbene derived from 3-(3//-diazirino)pyridine adenine dinucleotide (248). 

See also Diabetes, Hormone Receptors, Protein Kinase C... 

Fig. 10.3. General structural features of steroid hormone-receptor proteins.

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