Interdependence between a 55 kDa Protein (p55) and a 12 kDa Protein (p12) in Facilitating the Nuclear Entry of Goat Uterine Estrogen Receptor under Cell-Free Conditions

Padma, A.; Thampan, Raghava Varman

doi:10.1515/bc.2000.037

Cited by 8 publications

(5 citation statements)

References 41 publications

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“…The progesterone receptors apparently have the capacity to efflux from the nucleus under some conditions of ATP depletion while glucocorticoid receptors that are imported to the nuclei appear to remain within that compartment upon ATP depletion [Guiochon‐Mantel et al, 1991; Hu et al, 1994]. The role of ATP in estrogen receptor nuclear import pathway has been studied earlier [Sai Padma and Thampan, 2000]. The involvement of ATP hydrolysis for nuclear export was addressed.…”

Section: Discussionmentioning

confidence: 99%

Nuclear estrogen receptor II (nER‐II) is involved in the estrogen‐dependent ribonucleoprotein transport in the goat uterus: II. isolation and characterization of three small nuclear ribonucleoprotein proteins which bind to nER‐II

Sebastian

Thampan

2001

J of Cellular Biochemistry

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Three proteins of a goat uterine small nuclear ribonucleoprotein (snRNP) fraction, which bind to nuclear estrogen receptor-II (nER-II) have been isolated and purified. These are the p32, p55, and p60 of which p32 is the major nER-II binding protein. Indirect evidence reveals that p32 binds to the nuclear export signal (NES) on the nER-II. nER-II is a snRNA binding protein while p32 does not bind to the RNA. nER-II along with p32 and p55 form an effective Mg(++)ATPase complex, the activation of which appears to be the immediate reason behind the RNP exit from the nuclei following estradiol exposure. The three nER-II binding proteins bind to the nuclear pore complex; nER-II does not possess this property.

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Section: Discussionmentioning

confidence: 99%

Nuclear estrogen receptor II (nER‐II) is involved in the estrogen‐dependent ribonucleoprotein transport in the goat uterus: II. isolation and characterization of three small nuclear ribonucleoprotein proteins which bind to nER‐II

Sebastian

Thampan

2001

J of Cellular Biochemistry

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“…This observation indicated that p66 was in a position to interact with both ap55 and E‐RAF. Previous reports published from this laboratory demonstrated the existence of a 55 kDa protein that transports the regular estrogen receptor to the goat uterine nucleus [Nirmala and Thampan, 1995; Sai padma and Thampan, 2000] and a 62 kDa protein that transports the naER to the nucleus [Sreeja and Thampan, manuscript communicated]. It was decided to check the possibility whether the 66 kDa protein identified in the present study is the much sought after transport protein that transports E‐RAF to the nucleus.…”

Section: Resultsmentioning

confidence: 99%

Estradiol dependent anchoring of the goat uterine estrogen receptor activation factor (E‐RAF) at the endoplasmic reticulum by a 55 kDa anchor protein (ap55)

Govind

Sreekumar

Thampan

2003

J of Cellular Biochemistry

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The primary intracellular site of localization of the estrogen receptor activation factor (E-RAF) is shown here to be the endoplasmic reticulum where the protein remains anchored through an estrogen dependent mechanism. The retention of E-RAF by the endoplasmic reticulum is facilitated by two proteins: (1) a 55 kDa anchor protein (ap55) which is an integral membrane protein of the endoplasmic reticulum. ap55 is a high affinity estrogen binding protein. A conformational change induced by estrogen binding is thought to favor the anchoring process. (2) The anchoring of E-RAF by ap55 is mediated by yet another protein. This is the 66 kDa transport protein (tp66) which recognizes ap55 on the one hand and E-RAF on the other. The presence of estradiol that saturates the hormone binding sites on ap55 appears to favor the anchoring of tp66-E-RAF complex to ap55. This interaction appears to be weakened by levels of estradiol below 7 nM concentration leading to the dissociation of the tp66-E-RAF complex from ap55. The tp66-E-RAF complex moves towards the nucleus.

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“…Purification of p12 was achieved following the method described by Sai Padma and Thampan [2000]. p12 is the nuclear pore complex-associated protein that binds p55.…”

Section: Preparation Of Affinity Matricesmentioning

confidence: 99%

Protein-protein interactions that precede the nuclear entry of goat uterine estrogen receptor under cell-free conditions

2000

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Mechanisms associated with a regulated nuclear entry of the goat uterine estrogen receptor (gER), under the influence of estradiol, have been examined using a cell-free system. The gER transport into the nucleus is mediated by a 55-kDa cytosolic protein, p55. Experimental evidence has been provided to demonstrate that p55 binds to the nuclear localization signals (NLS) on the gER. Under hormone-free conditions, a 28-kDa protein, p28, binds to the NLS and prevents the p55 interaction with the NLS. This inhibition is reversed by a 73-kDa protein, p73. It appears that p73 associates with the hormone binding domain (HBD) of the gER under hormone-free conditions. Estradiol binding to the HBD facilitates p73 interaction with p28. This leads to the dissociation of p28 from the NLS, which, in turn, facilitates the binding of p55 to the NLS on the gER. Both p28 and p55 cross-react with monoclonal antibodies against hsp-25 and hsp-70, indicating a possibility that p28 and p55 belong to a superfamily of molecular chaperones. J. Cell. Biochem. 78:650-665, 2000.

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Interdependence between a 55 kDa Protein (p55) and a 12 kDa Protein (p12) in Facilitating the Nuclear Entry of Goat Uterine Estrogen Receptor under Cell-Free Conditions

Cited by 8 publications

References 41 publications

Nuclear estrogen receptor II (nER‐II) is involved in the estrogen‐dependent ribonucleoprotein transport in the goat uterus: II. isolation and characterization of three small nuclear ribonucleoprotein proteins which bind to nER‐II

Nuclear estrogen receptor II (nER‐II) is involved in the estrogen‐dependent ribonucleoprotein transport in the goat uterus: II. isolation and characterization of three small nuclear ribonucleoprotein proteins which bind to nER‐II

Estradiol dependent anchoring of the goat uterine estrogen receptor activation factor (E‐RAF) at the endoplasmic reticulum by a 55 kDa anchor protein (ap55)

Protein-protein interactions that precede the nuclear entry of goat uterine estrogen receptor under cell-free conditions

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