Tandem sequences defined

A delineated class of DNA, minisatellite DNA, has been found to be moderately to extremely variable in certain eukaryote genomes.1-3 Minisatellite DNA is composed of tandem repeats of a core or consensus sequence reiterated a low to moderate number of times (relative to satellite DNA, where consensus motifs, or variants thereon, may be repeated tens of thousands of times). For convenience, minisatellite DNA as defined here includes simple sequence4 and microsatellite5 DNA. Thus, minisatellite consensus sequences range from 2 to approximately 70 base pairs (bp). Several different minisatellite families (members of a family have consensus sequence similarities) have been described.6... 

Members of the PLD superfamily that exhibit PLD activity contain four conserved sequences (I—IV) of which sequences I and IV contain the HKD motifs [4] (Fig. 4.1). The functions of sequences I and III have not been defined, but it is assumed they participate in catalysis. Two adjacent domains, PX (Phox homology) and PH (pleckstrin homology), are located in the N-terminal sequences of mammalian, yeast and nematode PLDs and in the plant PLD C isozymes, but are absent from bacterial and most plant enzymes [5, 6]. The plant PLDs lacking the PX/PH tandem domain contain a Ca /phospholipid binding domain, designated C2, at the N-terminus and require Ca for activity [6]. 

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