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- ******************************
- * 5'-nucleotidase signatures *
- ******************************
-
- 5'-nucleotidases (EC 3.1.3.5) [1] are enzymes that catalyze the hydrolysis of
- phosphate esterified at carbon 5' of the ribose and deoxyribose portions of
- nucleotide molecules. 5'-nucleotidase is a ubiquitous enzyme found in a wide
- variety of species and which occurs in different cellular locations. The
- sequences of the following 5'-nucleotidases are currently known:
-
- - Extracellular 5'-nucleotidase from mammals and electric ray. This isozyme
- is a homodimeric disulfide-bonded glycoprotein attached to the membrane by
- a GPI-anchor. It requires zinc for its activity
- - Vibrio parahaemolyticus 5'-nucleotidase (gene nutA). This isozyme is bound
- to the membrane by a lipid chain. NutA requires chloride and magnesium
- ions for its activity. It is involved in degrading extracellular
- 5'-nucleotides for nutritional needs.
- - Periplasmic bacterial 5'-nucleotidase (gene ushA). This enzyme, also known
- as UDP-sugar hydrolase (EC 3.6.1.45), can degrade UDP-glucose and other
- nucleotide diphosphate sugars. It produces sugar-1-phosphate which can
- then be used by the cell. UshA seems to require cobalt for its activity.
-
- 5'-nucleotidases are evolutionary related to the following enzyme:
-
- - Periplasmic bacterial 2',3'-cyclic-nucleotide 2'-phosphodiesterase (EC 3.1.
- 4.16) (gene cpdB). This bifunctional enzyme catalyzes two consecutive
- reactions: it first converts 2',3'-cyclic-nucleotide to 3'-nucleotide and
- then acts as a 3'-nucleotidase.
-
- All these proteins share a number of regions of sequence similarity, of which
- we selected two as signature patterns. Both regions are located in the N-
- terminal section of these enzymes. The second pattern contains a perfectly
- conserved pentapeptide.
-
- -Consensus pattern: [LIVM]-x-[LIVM](2)-[HE]-T-x-D-x-H-[GSA]
- -Sequences known to belong to this class detected by the pattern: ALL.
- -Other sequence(s) detected in SWISS-PROT: NONE.
-
- -Consensus pattern: Y-x(4)-[LIVM]-G-N-H-E-F-[DN]
- -Sequences known to belong to this class detected by the pattern: ALL.
- -Other sequence(s) detected in SWISS-PROT: NONE.
-
- -Last update: June 1994 / Text revised.
-
- [ 1] Zimmermann H.
- Biochem. J. 285:345-365(1992).
-