Ligand-binding studies with a 23 kDa protein purified from bovine brain cytosol

Raf Kinase Inhibitory Protein (RKIP): Functional Pleiotropy in the Mammalian Brain

“…19,20 Within the cell, both the work of Bernier et al and the subsequent elucidation of the crystal structure of RKIP suggest strongly that RKIP is associated with the inner leaflet of the plasma membrane, where it is ideally situated to transduce signals from the membrane to the cytoplasm. 2,21 On the other hand, immunohistochemical studies have revealed that RKIP may be expressed in multiple subcellular compartments, depending on the cell type or condition: RKIP is localized predominantly in the cytoplasm and at the plasma membrane, with occasional expression detected within the nucleus. [22][23][24] The function of nuclear RKIP is unclear, although Eves et al have shown that RKIP may associate with centrosomes and kinetochores to regulate the spindle checkpoint of mitotic cells.…”

“…1 Ligand binding studies revealed that this protein could bind in a specific manner to phosphatidylethanolamine (PE), a class of phospholipids that is localized to the cytoplasmic leaflet of the plasma membrane. 2 As a result, the protein was designated phosphatidylethanolamine-binding protein 1 (PEBP1), which remains the official name of the encoding gene. Progress in understanding the physiological functions of PEBP1 was modest.…”

From structure to function: possible biological roles of a new widespread protein family binding hydrophobic ligands and displaying a nucleotide binding site

“…When studying the affinity of the bovine brain 21 23 kDa protein for phosphatidylethanolamine, Bernier et al [8] observed that addition of increasing amounts of phosphatidylethanolamine to a constant amount of protein induced the formation of polymers. With low amounts of phosphatidylethanolamine, up to a molecular ratio (protein/phosphatidylethanolamine) of about 1:4, no polymerization occurred, while with increasing phospholipid concentrations SDS/PAGE demonstrated first the appearance of dimers and later, of polymers.…”

“…At present, there is no explanation for this discrepancy: it might be due to differences in post-translational events or to 3D structure modifications. However, according to its apparent higher molecular weight, we call the protein encountered in the testis 'testicular phosphatidylethanolamine binding protein' (tPBP) in reference to the initial properties shown for the bovine brain 21-23 kDa protein [8] and to the evidence that the testicular protein is able to bind phosphatidylethanolamine in vitro [21].…”

“…We identified a basic, cytosolic protein from bovine brain [7], belonging to this hydrophobic ligand bindingprotein family. It had a molecular mass of about 23 was shown to be an anion-binding protein: later, it was characterized as a phosphatidylethanolamine binding protein [8]. The amino acid sequence showed that the 23 kDa protein might represent a new protein family and that its correct molecular weight was 21 kDa [9]; thus, it was called 21-23 kDa protein.…”