Abstract
We have purified two 35 kd phospholipase A2 inhibitors from human placenta, which we refer to as lipocortin I and II. Both proteins exhibit similar biochemical properties and occur in placenta at about 0.2% of the total protein. By peptide mapping, sequence, and immunological analyses, we show that lipocortin I and the 35 kd substrate for the EGF-receptor/kinase from A431 cells are the same protein. By similar criteria, we determine that lipocortin II is the human analogue of pp36, a major substrate for pp60src, which has been characterized in chicken embryo fibroblasts and in bovine brush border preparations. The amino acid sequences of lipocortin I and II that we deduced from cDNA clones share 50% homology, indicating that they probably evolved from a common gene.
MeSH terms
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Amino Acid Sequence
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Annexins
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Avian Sarcoma Viruses
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DNA / isolation & purification
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Epidermal Growth Factor / metabolism*
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ErbB Receptors
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Female
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Glycoproteins / isolation & purification*
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Humans
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Membrane Proteins / isolation & purification
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Molecular Weight
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Peptide Fragments / isolation & purification
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Phospholipases / antagonists & inhibitors*
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Phospholipases A / antagonists & inhibitors*
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Phospholipases A2
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Pregnancy
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Pregnancy Proteins / isolation & purification
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Protein-Tyrosine Kinases / metabolism*
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Receptors, Cell Surface / metabolism*
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Retroviridae Proteins / metabolism*
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Transducin
Substances
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Annexins
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Glycoproteins
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Membrane Proteins
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Peptide Fragments
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Pregnancy Proteins
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Receptors, Cell Surface
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Retroviridae Proteins
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Epidermal Growth Factor
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DNA
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ErbB Receptors
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Protein-Tyrosine Kinases
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Phospholipases
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Phospholipases A
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Phospholipases A2
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Transducin