Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04626 (erbB-2)
 5,251 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Many plasma membrane proteins, including the epidermal growth factor (EGF) receptor, possess basic regions on the cytoplasmic surface of the membrane. To examine the function of these positively charged regions, we constructed mutated EGF receptor genes lacking this region by substitution of the basic amino acid residues with 3 approximately 8 neutral Asn residues, or by their complete deletion. There was no significant difference in the affinities for EGF of the wild-type and mutant receptors which are produced in rodent fibroblasts through transfection. However, EGF-induced tyrosine phosphorylation of the receptor was strongly inhibited by removal of the 3 approximately 8 positively charged residues. On addition of EGF, cells expressing the mutant EGF receptors did not show morphological changes, whereas cells expressing the wild-type receptor did. These findings suggest that the positively charged regions of membrane proteins that are asymmetrically distributed on the cytoplasmic surface of the membrane may be required for the functions of membrane proteins in general.
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PMID:Ligand-induced functions of the epidermal growth factor receptor require the positively charged region asymmetrically distributed across plasma membrane. 131 70

An epidermal growth factor (EGF) receptor monoclonal antibody (mAb), mAb LA22, was used to analyze the covalent coupling of human EGF receptors to mouse EGF by the amine-reactive cross-linking agent disuccinimidyl suberate. A soluble Mr 105,000 truncated form of the receptor secreted by A-431 epidermoid carcinoma cells and consisting of the ligand-binding extracellular domain was cross-linked to 125I-labeled EGF. Digestion of this complex with an endoproteinase that specifically cleaves at the COOH side of glutamyl residue released a single radiolabeled glycosylated fragment of Mr 18,000 that reacted with mAb LA22. As the epitope for mAb LA22 resided between Ala-351 and Asp-364 of the mature receptor, this result localized the cross-linked receptor residue(s) to the 47-amino acid interval from Phe-321 to Glu-367. The receptor residue(s) involved in the covalent coupling of rat 125I-labeled transforming growth factor alpha was similarly localized to this region of the receptor. This receptor interval, which included two glycosylated asparaginyl residues at positions 328 and 337, contained but three amino acid residues that were potentially reactive with disuccinimidyl suberate: Lys-332, Lys-333, and Lys-336. Characterization of mAb LA22-reactive 125I-EGF-labeled receptor fragments generated by an endoproteinase specific for the COOH side of lysyl residue placed the NH2 termini of the two smallest fragments between the glycosylated residues Asn-328 and Asn-337. These results indicated that disuccinimidyl suberate cross-linked the NH2 group of EGF residue Asn-1 to the human EGF receptor residue Lys-336. Our results further suggest that EGF and transforming growth factor alpha, two members of the EGF family of peptide growth factors, interact with closely apposed or identical features of the receptor.
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PMID:Human epidermal growth factor receptor residue covalently cross-linked to epidermal growth factor. 169 2

The phage library derived, nonphosphorylated and thioether-cyclized peptide, termed G1TE, cyclo(CH(2)CO-Glu(1)-Leu-Tyr(3)-Glu-Asn-Val-Gly-Met-Tyr-Cys(10))-amid e, represents a new structural motif that binds to the Grb2-SH2 domain in a pTyr-independent manner, with an IC(50) of 20 microM. The retention of binding affinity is very sensitive with respect to peptide ring-size alterations and Ala mutations. We demonstrated previously that the Glu(1) side chain and its closely related analogs partially compensate for the absence of the phosphate functionality on Tyr(3), and, based on molecular modeling, these acidic side-chains complex with the Arg67 and Arg86 side-chains of the protein in the binding cavity. In this study we judiciously altered and incorporated various natural and unnatural amino acids as Tyr replacements within the -YEN- motif, and we demonstrate the functional importance and structural requirement of Tyr(3) for effective binding of this novel non-phosphorylated ligand to the Grb2-SH2 domain. The phenyl side-chain moiety and a polar functional group with specific orientation in position Y(3) of the peptide are particularly required. Using SPR binding assays, a submicromolar inhibitor (IC(50) = 0.70 microM) was obtained when Glu(1) was replaced with alpha-aminoadipate and Tyr(3) was replaced with 4-carboxymethyl-Phe, providing peptide 14, G1TE(Adi(1), cmPhe(3)). Peptide 14 also inhibited Grb2/p185(erb)(B-2) protein association in cell homogenates of erbB-2-overexpressing MDA-MA-453 cancer cells at near one micromolar concentrations.
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PMID:Structural requirements for Tyr in the consensus sequence Y-E-N of a novel nonphosphorylated inhibitor to the Grb2-SH2 domain. 1054 28

High affinity binding of peptides to Src homology 2 (SH2) domains, often requires the presence of phosphotyrosyl (pTyr) or pTyr-mimicking moieties in the N-terminal position of the binding ligand. Several reports have shown that N(alpha)-acylation of the critical pTyr residue can result in increased SH2 domain binding potency. For Grb2 SH2 domains which recognize pTyr-Xxx-Asn-NH(2) motifs, significant potency enhancement can be incurred by N(alpha)-(3-amino)Z derivatization of tripeptides such as pTyr-Ile-Asn-NH(2). Using ligands based on the high affinity pY-Ac(6)c-Asn-(naphthylpropylamide) motif, (where Ac(6)c=1-aminocyclohexanecarboxylic acid), additional reports have shown moderate potentiating effects of N(alpha)-oxalyl derivatization. The current study examined variations of the N(alpha)-oxalyl theme in the context of a Xxx-Ac(6)c-Asn-(naphthylpropylamide) platform, where Xxx=the hydrolytically stable pTyr mimetics phosphonomethyl phenylalanine (Pmp) or carboxymethyl phenylalanine (Cmf). The effects of N(alpha)-(3-amino)Z derivatization were also investigated for this platform, to ascertain whether the large binding enhancement reported for tripeptides such as pTyr-Ile-Asn-NH(2) could be observed. In ELISA-based extracellular Grb2 SH2 domain binding assays, it was found for the Pmp-based series, that extending the oxalyl carboxyl out by one methylene unit or replacing carboxyl functionality with a tetrazole isostere, resulted in binding potency greater than the parent N(alpha)-acetyl-containing compound, with enhancement approximating that observed for the N(alpha)-oxalyl derivative. When Cmf was used as the pTyr mimetic, only modest differences in IC(50) values were observed for the series. Examination of the N(alpha)-(3-amino)Z derivatized Pmp-Ac(6)c-Asn-(naphthylpropylamide), showed that binding affinity was reduced relative to the parent N(alpha)-acetyl analogue, in contrast to the reported significant enhancement of affinity observed with other peptide ligands. Treatment of MDA-453 tumor cells, which are mitogenically driven through erbB-2 tyrosine kinase-dependent pathways, with Pmp-containing inhibitors resulted in growth inhibition, with the N(alpha)-oxalyl and N(alpha)-malonyl-containing compounds exhibiting IC(50) values (4.3 and 4.6 microM, respectively) approximately five-fold lower than the parent N(alpha)-acetyl-containing compound. Tetrazole and N(alpha)-(3-amino)Z-containing inhibitors were from two- to four-fold less potent than these latter analogues in the growth inhibition assays.
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PMID:N-terminal carboxyl and tetrazole-containing amides as adjuvants to Grb2 SH2 domain ligand binding. 1140 62

Aberrant protein glycosylation could be a distinct surface-marker of cancer cells that influences cancer progression and metastasis because glycosylation can regulate membrane protein folding which alters receptor activation and changes epitope exposure for antibody (Ab) recognition. Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6), a glycophosphoinositol-anchored protein, is a heavily glycosylated tumor antigen. However, the clinical significance and biological effect of CEACAM6 glycosylation has not been addressed in cancers. We recently developed an anti-CEACAM6 Ab (TMU) from an immune llama library which can be engineered to a single-domain (sd)Ab or a heavy-chain (HC)Ab. The TMU HCAb specifically recognized glycosylated CEACAM6 compared to the conventional antibodies. Using the TMU HCAb, we found that glycosylated CEACAM6 was a tumor marker associated with recurrence in early-stage OSCC (oral squamous cell carcinoma) patients. CEACAM6 promoted OSCC cell invasion, migration, cytoskeletal rearrangement, and metastasis via interaction with epidermal growth factor (EGF) receptor (EGFR) and enhancing EGFR activation, clustering and intracellular signaling cascades. These functions were modulated by N-acetylglucosaminyltransferase 5 (MGAT5) which mediated N-glycosylation at Asn256 (N256) of CEACAM6. Finally, the TMU sdAb and HCAb treatment inhibited the migration, invasion and EGF-induced signaling in CEACAM6-overexpressing cells. In conclusion, the complex N-glycosylation of CEACAM6 is critical for EGFR signaling of OSCC invasion and metastasis. Targeting glycosylated CEACAM6 with the TMU sdAb or TMU HCAb could be a feasible therapy for OSCC.
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PMID:Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) promotes EGF receptor signaling of oral squamous cell carcinoma metastasis via the complex N-glycosylation. 2889 50