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Papers by Janmeet Anant
Bioreactors for Stem Cell Expansion and Differentiation, 2018
Journal of Biological Chemistry, 1992
Biochemical Society Transactions, 1996
Protein prenylation is a type of lipid modification that affects about 0.5% of cellular proteins ... more Protein prenylation is a type of lipid modification that affects about 0.5% of cellular proteins [l]. Prenylated proteins are covalently modified with either farnesyl or geranylgeranyl (GG) via thioether bonds to C-terminal cysteine residues
Methods in Enzymology, 1994
ABSTRACT Several approaches have been developed for the identification of isoprenyl groups on mod... more ABSTRACT Several approaches have been developed for the identification of isoprenyl groups on modified proteins. The first, and most rigorous, involves chemical cleavage of the modifying isoprenyl group with Raney nickel, followed by gas chromatography-coupled mass spectrometric (GC–MS) analysis of the products. The advantage of GC–MS analysis is that definitive identification of the isoprenyl group, as well as its stereochemical configuration, can be determined. This chapter describes a detailed protocol for the GC–MS analysis of isoprenylated proteins. There are also two variations of this approach. The first involves the release of the modifying isoprenoid with methyl iodide, followed by the separation of the resulting products by high-performance liquid chromatography (HPLC) and structural analysis by GC–MS. This method, however, does not allow the rigorous assignment of the stereochemistry of the modifying isoprenyl group. The second variation employs atom bombardment mass spectrometry to determine the combined mass value of the isoprenylated polypeptide. This information is then used to deduce the identity of the isoprenyl group if the exact amino acid sequence of the polypeptide is known.
Journal of Biological Chemistry, 1995
Gene, 1999
... This fact makes Rab27 a possible trigger for the retinal degeneration in CHM ( Seabra et al.,... more ... This fact makes Rab27 a possible trigger for the retinal degeneration in CHM ( Seabra et al., 1995). ... DNA was subjected to standard agarose gel electrophoresis or to PFGE in 0.5×TBE with 510 s switching for 18 h. The DNA was transferred onto Hybond N + nylon membrane ...
Biochemistry, 1998
Rab proteins are geranylgeranylated on one or two C-terminal cysteines by Rab geranylgeranyl tran... more Rab proteins are geranylgeranylated on one or two C-terminal cysteines by Rab geranylgeranyl transferase (RabGGTase). The reaction is dependent on a Rab-binding protein, termed Rab escort protein (REP). Here, we studied the role of REP in the geranylgeranylation reaction. We first characterized the interaction between REP and ungeranylgeranylated Rab using analytical ultracentrifugation and a fluorescence-based assay. We measured an equilibrium dissociation constant of 0.2 µM for the formation of a 1:1 REP-Rab complex and showed that this interaction relies mostly on ionic bonds and does not involve the two C-terminal cysteine residues. Second, we show that REP is required for recognition of Rab by RabGGTase and therefore that the REP-Rab complex is the true substrate for RabGGTase. Third, we show that free REP inhibits the geranylgeranylation reaction, suggesting that the complex is recognized by RabGGTase primarily via a REP-binding site. Our data suggest a model whereby REP behaves kinetically as an essential activator of the reaction.
Biochemical and Biophysical Research Communications, 1992
We have shown by intravitreal injection of [3H]mevalonolactone that a 65 kDa protein in rat photo... more We have shown by intravitreal injection of [3H]mevalonolactone that a 65 kDa protein in rat photoreceptors is posttranslationally modified by farnesylation. We further identified this 65 kDa prenylated protein as rhodopsin kinase based on its affinity for photolyzed rhodopsin and its ability to autophosphorylate in the presence of [gamma-32P]ATP. The farnesylation of rhodopsin kinase may be important for correctly targeting this enzyme to the photoreceptor outer segments, allowing it to phosphorylate photolyzed rhodopsin efficiently.
Bioreactors for Stem Cell Expansion and Differentiation, 2018
Journal of Biological Chemistry, 1992
Biochemical Society Transactions, 1996
Protein prenylation is a type of lipid modification that affects about 0.5% of cellular proteins ... more Protein prenylation is a type of lipid modification that affects about 0.5% of cellular proteins [l]. Prenylated proteins are covalently modified with either farnesyl or geranylgeranyl (GG) via thioether bonds to C-terminal cysteine residues
Methods in Enzymology, 1994
ABSTRACT Several approaches have been developed for the identification of isoprenyl groups on mod... more ABSTRACT Several approaches have been developed for the identification of isoprenyl groups on modified proteins. The first, and most rigorous, involves chemical cleavage of the modifying isoprenyl group with Raney nickel, followed by gas chromatography-coupled mass spectrometric (GC–MS) analysis of the products. The advantage of GC–MS analysis is that definitive identification of the isoprenyl group, as well as its stereochemical configuration, can be determined. This chapter describes a detailed protocol for the GC–MS analysis of isoprenylated proteins. There are also two variations of this approach. The first involves the release of the modifying isoprenoid with methyl iodide, followed by the separation of the resulting products by high-performance liquid chromatography (HPLC) and structural analysis by GC–MS. This method, however, does not allow the rigorous assignment of the stereochemistry of the modifying isoprenyl group. The second variation employs atom bombardment mass spectrometry to determine the combined mass value of the isoprenylated polypeptide. This information is then used to deduce the identity of the isoprenyl group if the exact amino acid sequence of the polypeptide is known.
Journal of Biological Chemistry, 1995
Gene, 1999
... This fact makes Rab27 a possible trigger for the retinal degeneration in CHM ( Seabra et al.,... more ... This fact makes Rab27 a possible trigger for the retinal degeneration in CHM ( Seabra et al., 1995). ... DNA was subjected to standard agarose gel electrophoresis or to PFGE in 0.5×TBE with 510 s switching for 18 h. The DNA was transferred onto Hybond N + nylon membrane ...
Biochemistry, 1998
Rab proteins are geranylgeranylated on one or two C-terminal cysteines by Rab geranylgeranyl tran... more Rab proteins are geranylgeranylated on one or two C-terminal cysteines by Rab geranylgeranyl transferase (RabGGTase). The reaction is dependent on a Rab-binding protein, termed Rab escort protein (REP). Here, we studied the role of REP in the geranylgeranylation reaction. We first characterized the interaction between REP and ungeranylgeranylated Rab using analytical ultracentrifugation and a fluorescence-based assay. We measured an equilibrium dissociation constant of 0.2 µM for the formation of a 1:1 REP-Rab complex and showed that this interaction relies mostly on ionic bonds and does not involve the two C-terminal cysteine residues. Second, we show that REP is required for recognition of Rab by RabGGTase and therefore that the REP-Rab complex is the true substrate for RabGGTase. Third, we show that free REP inhibits the geranylgeranylation reaction, suggesting that the complex is recognized by RabGGTase primarily via a REP-binding site. Our data suggest a model whereby REP behaves kinetically as an essential activator of the reaction.
Biochemical and Biophysical Research Communications, 1992
We have shown by intravitreal injection of [3H]mevalonolactone that a 65 kDa protein in rat photo... more We have shown by intravitreal injection of [3H]mevalonolactone that a 65 kDa protein in rat photoreceptors is posttranslationally modified by farnesylation. We further identified this 65 kDa prenylated protein as rhodopsin kinase based on its affinity for photolyzed rhodopsin and its ability to autophosphorylate in the presence of [gamma-32P]ATP. The farnesylation of rhodopsin kinase may be important for correctly targeting this enzyme to the photoreceptor outer segments, allowing it to phosphorylate photolyzed rhodopsin efficiently.