HIP-70: a Protein Induced by Estrogen in the Brain and LH-RH in the Pituitary

Mobbs, CV; Fink, George; Pfaff, D. W.

doi:10.1126/science.2181662

Cited by 51 publications

(19 citation statements)

References 16 publications

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“…Although repeated searches on Genbank before our report was submitted revealed no sequence similarities between the NH2-terminus of HIP-70 and any other sequence, more recent searches on Genbank revealed an identity (first brought to our attention by M. Christensen) with the NH2-terminus of a phosphoinositide-specific phospholipase C (PI-PLC) isoenzyme (2 (1), which is consistent with the hypothesis that phosphorylation may attenuate the activation of PLC-a (5). HIP-70 seems to be the most basic of four isoforms from brain that are recognized by an antibody to PLC-a (6).…”

supporting

confidence: 58%

“…We recently reported that estrogen and luteinizing hormone-releasing hormone (LH-RH) induce the same protein, which we referred to as HIP-70 (1). Although repeated searches on Genbank before our report was submitted revealed no sequence similarities between the NH2-terminus of HIP-70 and any other sequence, more recent searches on Genbank revealed an identity (first brought to our attention by M. Christensen) with the NH2-terminus of a phosphoinositide-specific phospholipase C (PI-PLC) isoenzyme (2 (1), which is consistent with the hypothesis that phosphorylation may attenuate the activation of PLC-a (5).…”

mentioning

confidence: 99%

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HIP-70: An Isoform of Phosphoinositol-Specific Phospholipase C—α

Mobbs

Fink

Pfaff

1990

Science

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depth. However, Deutsch and Ramachandran's example of a crumpled newspaper clearly shows that this is not the only factor involved. In this case there is an abundance of high contrast local disparity information provided by the printed letters, yet the pseudoscopic image cannot be reversed in depth. This is also true if the words and letters are completely unintelligible. Likewise, pseudoscopic viewing of the normal face of our original figure 5 (1), upsidedown or partially covered, does not make the nose reverse. We therefore feel confident that the binocular interpretation of texture perspective (2) and not familiarity counter-

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supporting

confidence: 58%

mentioning

confidence: 99%

HIP-70: An Isoform of Phosphoinositol-Specific Phospholipase C—α

Mobbs

Fink

Pfaff

1990

Science

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“…Over the years, ERp57 has emerged in the literature under various names, including ERp61 [32,33], HIP-70 [34], Q-2 [35], ER-60 [36], ERp60 [12,37] and P58 [38].…”

Section: Discussionmentioning

confidence: 99%

The transient association of ERp57 with N‐glycosylated proteins is regulated by glucose trimming

Wal

Oliver

High

1998

European Journal of Biochemistry

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The thiol-dependent reductase ERp57 has been shown to interact specifically with in vitro synthesised glycoproteins imported into canine pancreatic microsomes. On this basis, it was proposed that ERp57 forms part of a glycoprotein-specific folding 'machinery', present in the lumen of the endoplasmic reticulum (ER). In this study, we have investigated the interaction of ERp57 with newly synthesised proteins using semi-permeabilised mammalian cells (SP cells), in which the ER remains essentially intact and, hence, resembles that of a living cell. We demonstrate that ERp57 interacts preferentially with the glycosylated versions of soluble and membrane proteins, and that this interaction occurs in combination with calnexin and calreticulin. For the first time, we have performed a detailed analysis of the kinetics of ERp57 binding to newly synthesised glycoproteins. We find that ERp57 associates transiently with glycoproteins Ϫ a characteristic of molecular chaperones. Using mutant SP cells deficient in glucosidase I, we confirm that the binding of ERp57 to glycoproteins depends upon glucose trimming. We also demonstrate, for the first time, that the release of ERp57 from glycoprotein substrates is dependent upon glucose trimming. These data are combined to present a unified model for the role of ERp57/ER lectin complexes during glycoprotein folding in vivo.Keywords : endoplasmic reticulum ; ERp57/GRP58 ; molecular chaperone ; N-linked glycosylation; protein disulphide isomerase.The endoplasmic reticulum (ER) membrane is a primary site of protein synthesis in mammalian cells. Newly synthesised proteins are inserted into, or translocated across, the ER membrane, from where they can reach their final destination in one of the organelles of the secretory pathway, the plasma membrane or the cell exterior.To facilitate protein maturation, the ER is equipped with a number of membrane and soluble proteins involved in the processing, modification, folding and oligomeric assembly of newly synthesised polypeptides. ER proteins involved in protein maturation include folding enzymes, such as peptidylprolyl cisϪtrans isomerase and members of the protein disulphide isomerase (PDI) family, as well as molecular chaperones of the Hsp70 and Hsp90 class heat-shock proteins, such as immunoglobulin heavy-chain-binding protein (BiP/GRP78) and GRP94 [1].In addition to these folding enzymes and chaperones, the ER contains two proteins with lectin-like properties, namely the type-I membrane protein calnexin, and its soluble homologue, calreticulin. Calnexin and calreticulin associate transiently with a wide variety of N-glycosylated proteins, and were proposed to influence folding, oligomerisation and ER retention. Together with several enzymes that modify N-linked oligosaccharides, calnexin and calreticulin constitute an ER quality-control machinery for glycoproteins [2].Calnexin and calreticulin display a specificity for monoglucosylated oligosaccharides [2Ϫ4] that are generated in the ER by the combined actions of two A-glucosidases and a...

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“…This property is different from its direct releasing action and is dependent on de-novo synthesis of RNA and priming proteins (de Koning et al 1976, Pickering & Fink 1976, Mobbs et al 1990. Experimentally, GnRH self-priming is considered to be present when the magnitude of the LH response to the second (primed response) of two exposures to GnRH separated by an interval of 60 min is significantly greater than the response (unprimed response) to the first exposure of the pituitary to GnRH (de Koning et al 1976).…”

Section: Introductionmentioning

confidence: 99%

A paradoxical inhibitory effect of oestradiol-17β on GnRH self-priming in pituitaries from tamoxifen-treated rats

Sánchez-Criado

Bellido²,

Aguilar³

et al. 2005

Journal of Endocrinology

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Two-week ovariectomized (OVX) rats were injected over three days with 25 µg oestradiol benzoate (EB), 3 mg tamoxifen (TX) and 0·2 ml oil and their pituitaries were harvested for incubation experiments. Pituitaries from EBand TX-treated OVX rats exhibited GnRH self-priming when incubated with their corresponding ligand. However, incubation of pituitaries with different ligands yielded divergent results: when pituitaries from EBtreated rats were incubated with 10 7 M TX they displayed GnRH self-priming, whereas incubation of pituitaries from TX-treated rats with 10 8 M oestradiol-17 (E 2 ) blocked GnRH self-priming. Further studies to analyse the latter finding revealed that: (a) E 2 inhibited TX-induced GnRH self-priming in a dose-dependent manner while 10 8 M oestradiol-17 did not; (b) coincubation of E 2 with the pure anti-oestrogen ICI 182,780, but not with the selective oestrogen receptor modulator TX, reversed the E 2 inhibitory effect; (c) the oestrogen receptor (ER)-selective agonist propylpyrazole triol, but not the ER selective agonist diarylpropionitrile, mimicked the inhibitory effect of E 2 ; (d) the analogue membrane-impermeable conjugated E 2 -BSA also inhibited TX-induced GnRH self-priming; and (e) a 15-min exposure of the pituitaries to E 2 was sufficient to inhibit the GnRH self-priming elicited by TX. Although other explanations may exist, altogether these results suggested that E 2 , via an ER different from classical ER, inhibits the GnRH self-priming elicited by TX.

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HIP-70: a Protein Induced by Estrogen in the Brain and LH-RH in the Pituitary

Cited by 51 publications

References 16 publications

HIP-70: An Isoform of Phosphoinositol-Specific Phospholipase C—α

HIP-70: An Isoform of Phosphoinositol-Specific Phospholipase C—α

The transient association of ERp57 with N‐glycosylated proteins is regulated by glucose trimming

A paradoxical inhibitory effect of oestradiol-17β on GnRH self-priming in pituitaries from tamoxifen-treated rats

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