Small Molecular Weight GTP-binding Proteins in Human Platelet Membranes

Ohmori, Toshihiko; Kikuchi, Akira; Yamamoto, Katsuhiko; Kim, S; Takai, Yoshimi

doi:10.1016/s0021-9258(18)94269-9

Cited by 90 publications

(10 citation statements)

References 22 publications

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“…smg p25A and rhoB p20 were purified from bovine brain membranes Yamamoto et al, (1988). smg p2IB was purified from human platelet membranes (Ohmori et al, 1989). c-Ha-ras p21 was purified from human c-Ha-ras p21 expressing Escherichia coli, a gift from Drs.…”

Section: Methodsmentioning

confidence: 99%

Purification and characterization from rat liver cytosol of a GDP dissociation inhibitor (GDI) for liver 24K G, a ras p21-like GTP-binding protein, with properties similar to those of smg p25A GDI

Ueda¹,

Takeyama²,

Ohmori³

et al. 1991

Biochemistry

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A regulatory protein for a liver GTP-binding protein (G protein) with a molecular weight value of 24,000 (24K G), which we have recently purified, was purified to near-homogeneity from rat liver cytosol and characterized. This regulatory protein, designated here as GDP dissociation inhibitor for 24K G (24K G GDI), inhibited the dissociation of GDP from and the subsequent binding of GTP to 24K G. 24K G GDI was inactive for other ras p21/ras p21-like small G proteins including c-Ha-ras p21, rhoB p20, smg p21B, and smg p25A. 24K G was, however, recognized by bovine brain smg p25A GDI which regulated the GDP/GTP exchange reaction of smg p25A. By analyses of sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis (PAGE), immunoblotting with anti-smg p25A GDI antibody, two-dimensional PAGE, and C4 column chromatography, 24K G GDI showed physical properties very similar to those of smg p25A GDI. The peptide map and the partial amino acid sequences of 24K G GDI were not identical with those of smg p25A GDI. Among the 83 residues, 2 amino acids were different between rat liver 24K G GDI and bovine brain smg p25A GDI. These results indicate that there is a specific regulatory protein for 24K G, 24K G GDI, in rat liver cytosol and that 24K G GDI has close similarity to smg p25A GDI.

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Section: Methodsmentioning

confidence: 99%

Purification and characterization from rat liver cytosol of a GDP dissociation inhibitor (GDI) for liver 24K G, a ras p21-like GTP-binding protein, with properties similar to those of smg p25A GDI

Ueda¹,

Takeyama²,

Ohmori³

et al. 1991

Biochemistry

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“…The identified members of this set of proteins include the rho (Yamamoto et al, 1988), c- Ki-ras (Yamashita et al, 1988), rap-1 (Pizon et al, 1988), and rab-3 (Matsui et al, 1988) gene products. A similar set of low molecular weight GTP-binding proteins has also been isolated from platelets, including c-ras (Ohmori et al, 1989), ral, and rac-1 (Polakis et al, 1989b) gene products.…”

mentioning

confidence: 99%

Unique guanine nucleotide binding properties of the human placental GTP-binding protein Gp

Tamir

Fawzi²,

Northup³

1990

Biochemistry

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Gp is a major GTP-binding protein of human placenta and platelets [Evans, T., Brown, M. L., Fraser, E. D., & Northup, J. K. (1986) J. Biol. Chem. 261, 7052-7059]. High-affinity guanine nucleotide binding is associated with a polypeptide migrating identically with H-ras on SDS-PAGE. We have characterized the interactions of preparations of purified human placental Gp with guanine nucleotides in detergent solution. Equilibrium binding studies with [35S]GTP gamma S, [3H]Gpp(NH)p, and [3H]GTP identified a single class of sites with a dissociation constant of 10 +/- 1, 153 +/- 61, and 125 +/- 77 nM for the ligands, respectively. These three ligands were mutually competitive with Ki values consistent with the Kd values from direct binding experiments. Competition for the binding of [3H]Gpp(NH)p was used to determine the specificity of the site. Ki values determined from this assay were 14 nM for GTP gamma S, 143 nM for Gpp(NH)p, 3.3 microM for GDP beta S, 69 nM for GTP, and 64 nM for GDP. ATP, ADP, cAMP, cGMP, and NAD+ had no detectable affinity for this site. While the equilibrium binding data fit well to a single class of sites, association kinetics of these ligands were better fit to two rate constants. Dissociation kinetics, however, were not clearly resolved into two rates.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…calculated Mr values are 20,987 and 20,825, respectively (11,17). Both smg p21A and -B have the consensus amino acid sequences for GTPand GDP-binding and GTPase activities as described for other G proteins (11,17), and the purified proteins exhibit these activities (9,11,22). smg p21A and -B share 95% amino acid sequence homology and differ from each other by only 9 amino acids, 6 of which are clustered in the last 13 amino acid residues of the C terminus (11,17).…”

mentioning

confidence: 90%

“…However, the tissue distributions of the protein molecules of smg p2ls have not been studied. We have previously found that smg p21B is present abundantly in human platelet membranes and that the amount of this G protein in platelet membranes is at least 10 times higher than that of c-ras p21s (22). Moreover, we have found that smg p21B purified from bovine brain and human platelet membranes is phosphorylated by cyclic AMP-dependent protein kinase (protein kinase A) in a cell-free system and that it is also phosphorylated by the same protein kinase in intact human platelets in response to cyclic AMP-elevating prostaglandin E1 (6,10).…”

mentioning

confidence: 96%

Tissue and Subcellular Distributions of the smg-21/rap1/ Krev-1 Proteins Which Are Partly Distinct from Those of c-ras p21s

Kim

Mizoguchi

Kikuchi

et al. 1990

Molecular and Cellular Biology

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We have made a specific antiserum recognizing both smg p21A (the rap1A/Krev-1 protein) and -B (the rap1B protein), ras p21-like GTP-binding proteins having the same putative effector domain as ras p21s and have used this antiserum to study the tissue and subcellular distributions of smg p21s by immunoblot and immunocytochemical analyses. By immunoblot analysis, smg p21s were detected in various rat tissues and at the highest level in brain. By light microscopic immunocytochemical analysis, smg p21s were also detected in various rat tissues. Particularly, smg p21s in brain were found abundantly in the cytoplasmic region of most types of neuronal cell bodies and moderately in neuropil, whereas c-ras p21s were found more abundantly in neuropil than in the cytoplasmic region of most types of neuronal cell bodies. smg p21s in testis were found in spermatogenic cells, in which c-ras p21s were not significantly detected. By subcellular fractionation analysis of cerebrum, smg p21s were detected in all of the particulate fractions but not in the cytosol fraction. Among the particulate fractions, approximately 70% of smg p21s was recovered with the highest specific content in the fraction containing mainly synaptosomes, mitochondria, and myelin. In further fractionation of this fraction, approximately 40% of smg p21s was recovered in each of the synaptosome fraction and the mitochondrial fraction. This subcellular distribution of smg p21s in cerebrum was partly distinct from that of c-ras p21s, which were mainly recovered in the synaptosome and microsome fractions but present at very low levels in the mitochondrial fraction. These tissue and subcellular distributions of smg p 21s together with the fact that smg p21s have the same putative effector domain as ras p21s exert their own specific actions in addition to the actions similar or antagonistic to those of c-ras p21s.

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Small Molecular Weight GTP-binding Proteins in Human Platelet Membranes

Cited by 90 publications

References 22 publications

Purification and characterization from rat liver cytosol of a GDP dissociation inhibitor (GDI) for liver 24K G, a ras p21-like GTP-binding protein, with properties similar to those of smg p25A GDI

Purification and characterization from rat liver cytosol of a GDP dissociation inhibitor (GDI) for liver 24K G, a ras p21-like GTP-binding protein, with properties similar to those of smg p25A GDI

Unique guanine nucleotide binding properties of the human placental GTP-binding protein Gp

Tissue and Subcellular Distributions of the smg-21/rap1/ Krev-1 Proteins Which Are Partly Distinct from Those of c-ras p21s

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