Disease relevance of Tb11.02.5220

• Alkaline phosphatase extracted from human placental particulate fraction with butanol at pH 5.4 or released by incubation with Staphylococcus aureus phosphatidylinositol-specific phospholipase C produced a form of alkaline phosphatase of Mr approx. 170,000 and relatively low hydrophobicity [1].

High impact information on Tb11.02.5220

• The group includes the variant surface glycoprotein (VSG) of African trypanosomes, the p63 protein of Leishmania, acetylcholinesterase (AChE), alkaline phosphatase, Thy-1, 5'-nucleotidase, and RT6.2--an alloantigen from rat T cells [2].
• The COOH-terminal glycopeptide derived by Pronase digestion of soluble VSG was characterized by chemical modification and digestion with alkaline phosphatase [3].
• The membrane-bound histidine acid phosphatase TbMBAP1 is essential for endocytosis and membrane recycling in Trypanosoma brucei [4].
• The deduced amino acid sequences show a high degree of similarity to the catalytic subunit of protein phosphatase class 1 (PP1) genes [5].
• This could be explained by assuming a negative regulation, either directly or indirectly, of CRK by an OKA-sensitive phosphatase, which could be a PP2A as in the Xenopus oocyte and a positive regulation of kinetoplast replication by an OKA-susceptible protein(s) [6].

Biological context of Tb11.02.5220

• [3H]Phosphatidylinositol hydrolysis by the particulate fraction, unlike low Mr alkaline phosphatase production, was relatively sensitive to heat inactivation, indicating that the phosphoinositide-specific phospholipases C from cytosol and lysosomes were unlikely to be responsible for conversion [1].
• The tartrate-sensitive phosphatase was purified to homogeneity by monoclonal antibody affinity chromatography and shown to be a glycoprotein of low abundance (13,000 molecules/cell) [7].
• The deduced amino acid sequence has 39% and 55% identity, respectively, to the catalytic subunits of mammalian protein phosphatase 1 and 2A [8].
• Firstly, the stocks of T. b. rhodesiense were considerably more homogeneous than equivalent collections of stocks of T. b. brucei and secondly, all the stocks examined were heterozygous for two alleles of alkaline phosphatase and showed an excess of heterozygotes at the phosphoglucomutase locus [9].
• We conclude that both species of trypanosomes synthesize tyrosine phosphatases and propose that identification and characterization of the enzymes responsible for this phosphatase activity could provide information about trypanosomal virulence or the regulation of trypanosomal growth and differentiation [10].

Anatomical context of Tb11.02.5220

• Phosphoprotein phosphatase activity was found to be mainly soluble but a small part seemed to be associated with plasma membranes [11].

Associations of Tb11.02.5220 with chemical compounds

• The effect of a variety of inhibitors and activators on the amount of low Mr alkaline phosphatase produced during butanol extraction revealed that it was a Ca2+- and thiol-dependent process [1].
• Mr and hydrophobicity of the alkaline phosphatase were determined by gel filtration on TSK-250 and partitioning in Triton X-114, respectively [1].
• It has previously been suggested that the production of low Mr alkaline phosphatase during the commonly used butanol extraction procedure may result from the activation of an endogenous phosphoinositide-specific phospholipase C which removes the 1,2-diacylglycerol responsible for membrane anchoring [1].
• Subcellular distribution of adenylate cyclase, cyclic-AMP phosphodiesterase, protein kinases and phosphoprotein phosphatase in Trypanosoma brucei [11].
• The subcellular distribution of adenylate cyclase, cyclic-AMP phosphodiesterase, protein kinases and phosphoprotein phosphatase in bloodstream forms of Trypanosoma brucei was determined by isopycnic sucrose-gradient centrifugation of post-large-granule extracts [11].

Analytical, diagnostic and therapeutic context of Tb11.02.5220

• The PCR product was used to screen a T. b. rhodesiense cDNA library for cDNA clones encoding putative protein phosphatase catalytic subunits [8].
• Immunoblotting showed that BS7 cross-reacts with several cytoskeletal T. brucei proteins but phosphatase treatment did not diminish this complex immunoblot reactivity [12].

References