Recognizing the pleckstrin homology domain fold in mammalian phospholipaseD using hidden Markov models

Phospholipase D was first described in plant tissue but has recently been s hown to occur in mammalian cells where it is activated by cell surface rece ptors. Its mode of activation by receptors in unclear. Biochemical studies suggest that it may occur downstream of other effector proteins and that sm all GTP-dependent regulatory proteins may be involved. The sequence in a no n-designated region of mammalian phospholipase D1 and 2 shows similarity to a structural domain that is present in signalling proteins that are regula ted by protein kinases or heterotrimeric G-proteins. Mammalian phospholipas e D has structural similarities with other lipid signalling phospholipases and thus may be regulated by receptors in an analogous fashion. (C) 1999 Fe deration of European Biochemical Societies.