The epidermal growth factor precursor. A calcium-binding, beta-hydroxyasparagine containing modular protein present on the surface of platelets
| Autor: | Johan Stenflo, Ingemar Björk, C Valcarce |
|---|---|
| Rok vydání: | 1999 |
| Předmět: |
Blood Platelets
Male Protein Folding medicine.drug_class Molecular Sequence Data chemistry.chemical_element Calcium Biology Hydroxylation Monoclonal antibody Biochemistry Fluorescence Epidermal growth factor medicine Consensus sequence Humans Platelet Amino Acid Sequence Protein Precursors Peptide sequence Epidermal Growth Factor Molecular mass Calcium-Binding Proteins Antibodies Monoclonal Molecular biology chemistry Female Protein folding Asparagine Protein Processing Post-Translational hormones hormone substitutes and hormone antagonists |
| Zdroj: | European Journal of Biochemistry. 260:200-207 |
| ISSN: | 1432-1033 0014-2956 |
| Popis: | Various human body fluids and secretions contain a soluble form of the epidermal growth factor (EGF) precursor. The EGF precursor molecule contains eight EGF modules in addition to EGF itself. Using monoclonal antibodies specific for the EGF modules 7 and 8, we have purified the soluble form of the EGF precursor from human urine to homogeneity. The protein was shown to have a molecular mass of about 160 kDa and the N-terminal sequence SAPNHWSXPE. EGF modules 2, 7 and 8 of the precursor have the consensus sequence for post-translational beta-hydroxylation of Asp/Asn residues. We identified the presence of erythro-beta-hydroxy-aspartic acid (Hya) in acid hydrolysates of the EGF precursor (2.4 M.M protein-1). As the DNA sequence encodes Asn in the corresponding position, the Hya represents erythro-beta-hydroxyasparagine (Hyn). The Hyn-containing modules have a consensus calcium-binding motif immediately N-terminal of the first Cys residue. The synthetic EGF module 2 (residues 356-395) of the EGF precursor was found to bind calcium with low affinity, Kd approximately 3.5 mM, i.e. similar to the affinity of other isolated calcium-binding EGF modules. EGF module 7, when part of the intact protein, was found to bind Ca2+ with a Kd approximately 0.2 microM, i.e. approximately 10(4)-fold higher than that of isolated EGF modules presumably due to the influence of neighboring modules. We have detected EGF precursor in platelet-rich plasma and demonstrated it to be associated to platelets. The platelets were found to have 30-160 EGF molecules each. |
| Databáze: | OpenAIRE |
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