Two human 35 kd inhibitors of phospholipase A2 are related to substrates of pp60v-src and of the epidermal growth factor receptor/kinase.
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.
D000595:Amino Acid Sequence; D017302:Annexins; D001358:Avian Sarcoma Viruses; D004247:DNA / Q000302:isolation & purification; D004815:Epidermal Growth Factor / Q000378:metabolism*; D066246:ErbB Receptors; D005260:Female; D006023:Glycoproteins / Q000302:isolation & purification*; D006801:Humans; D008565:Membrane Proteins / Q000302:isolation & purification; D008970:Molecular Weight; D010446:Peptide Fragments / Q000302:isolation & purification; D010740:Phospholipases / Q000037:antagonists & inhibitors*; D010741:Phospholipases A / Q000037:antagonists & inhibitors*; D054467:Phospholipases A2; D011247:Pregnancy; D011257:Pregnancy Proteins / Q000302:isolation & purification; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D012191:Retroviridae Proteins / Q000378:metabolism*; D015293:Transducin
D017302:Annexins; D006023:Glycoproteins; D008565:Membrane Proteins; D010446:Peptide Fragments; D011257:Pregnancy Proteins; D011956:Receptors, Cell Surface; D012191:Retroviridae Proteins; D004815:Epidermal Growth Factor; D004247:DNA; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases; D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2; D015293:Transducin