Characterization of two structurally related Xenopus laevis protein tyrosine phosphatases with homology to lipid-binding proteins

Delvecchio, R. L., Tonks, N. K. (July 1994) Characterization of two structurally related Xenopus laevis protein tyrosine phosphatases with homology to lipid-binding proteins. Journal of Biological Chemistry, 269 (30). pp. 19639-19645. ISSN 0021-9258

URL: http://www.ncbi.nlm.nih.gov/pubmed/8034733

Abstract

We have chosen Xenopus laevis as a model system to study how protein tyrosine phosphatases (PTPases) function in growth and development. As an initial step, we have previously isolated in a polymerase chain reaction (PCR)-based protocol cDNA fragments which correspond to sequences within the catalytic domains of PTPases (Yang, and., and Tonks, N. K. (1993) Adv. Protein Phosphatases 7, 359-372). Two of these PCR products, designated X1 and X10, have now been used to screen a X. laevis ovary cDNA library to obtain complete coding sequences for two distinct PTPases. The X1 cDNA encodes a protein (PTPX1) of 693 amino acids (approximate to 79 kDa); the X10 cDNA encodes a protein of 597 amino acids (approximate to 69 kDa). Both PTPX1 and PTPX10 lack potential membrane spanning sequences and therefore can be classified as non-transmembrane/cytoplasmic PTPases. While the overall structure of these PTPases are similar, sharing segments of 95% amino acid identity, they differ in that PTPX1 contains a unique 97-amino acid insert between the N-terminal segment and C-terminal catalytic domain. The absence of complete identity between PTPX1 and PTPX10 suggests that these two sequences are the products of separate genes and not the result of alternative splicing. This conclusion is confirmed by PCR analysis of Xenopus genomic DNA. Both PTPases share sequence identities in their N-terminal segments with two lipid-binding proteins, cellular retinaldehyde-binding protein and SEC14p, a phospholipid transferase. In addition, the unique insert sequence of PTPX1 shares identity with PSSA, a protein involved in phosphatidylserine biosynthesis. Sequence comparison suggests that PTPX10 is the Xenopus homolog of the human PTPase Meg-02, while PTPX1 is a structurally related yet distinct PTPase, Intrinsic PTPase activity of PTPX1 and PTPX10 was demonstrated in lysates of Sf9 cells infected with recombinant baculoviruses encoding either enzyme. PTPX1 can be recovered in both soluble and membrane fractions from Xenopus oocytes with the membrane form exhibiting approximate to 4-fold higher activity than the soluble form.

Item Type: Paper
Uncontrolled Keywords: SH2-CONTAINING PHOSPHOTYROSINE PHOSPHATASE SEQUENCE HOMOLOGY EXPRESSION CLONING GENE PHOSPHORYLATION IDENTIFICATION PURIFICATION KINASES SITE
Subjects: bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > enzymes
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > enzymes > protein tyrosine phosphatase
organism description > animal > Frog > xenopus
CSHL Authors:
Communities: CSHL labs > Tonks lab
Depositing User: Matt Covey
Date: July 1994
Date Deposited: 17 Dec 2013 15:47
Last Modified: 17 Dec 2013 15:47
Related URLs:
URI: http://repository.cshl.edu/id/eprint/29069

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