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A novel family of P-loop NTPases with an unusual phyletic distribution and transmembrane segments inserted within the NTPase domain

L Aravind, Lakshminarayan M Iyer, Detlef D Leipe and Eugene V Koonin Address: National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA. reviews Correspondence: L Aravind. E-mail: aravind@ncbi.nlm.nih.gov Published: 16 April 2004 Genome Biology 2004, 5:R30 The electronic version of this article is the complete one and can be found online at http://genomebiology.com/2004/5/5/R30 Received: 19 January 2004 Revised: 8 March 2004 Accepted: 11 March 2004 reports © 2004 Aravind et al.; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided. | Open Access Research A novel family of P-loop NTPases with an unusual phyletic distribution and transmembrane segments inserted within the NTPase domain L Aravind Lakshminarayan M Iyer Detlef D Leipe and Eugene V Koonin Address National Center for Biotechnology Information National Library of Medicine National Institutes of Health Bethesda MD 20894 USA. Correspondence LAravind. E-mail aravind@ncbi.nlm.nih.gov Published 16 April 2004 Genome Biology 2004 5 R30 The electronic version of this article is the complete one and can be found online at http genomebiology.com 2004 5A5 R30 Received 19 January 2004 Revised 8 March 2004 Accepted 11 March 2004 2004 Aravind et al. licensee BioMed Central Ltd. This is an Open Access article verbatim copying and redistribution of this article are permitted in all media for any purpose provided this notice is preserved along with the article s original URL. Abstract Background Recent sequence-structure studies on P-loop-fold NTPases have substantially advanced the existing understanding of their evolution and functional diversity. These studies provide a framework for characterization of novel lineages within this fold and prediction of their functional properties. Results Using sequence profile searches and homology-based structure prediction we have identified a previously uncharacterized family of P-loop NTPases which includes the neuronal membrane protein and receptor tyrosine kinase substrate Kidins220 ARMS which is conserved in animals the F-plasmid PifA protein involved in phage T7 exclusion and several uncharacterized bacterial proteins. We refer to these predicted NTPases as the KAP family after Kidins220 ARMS and PifA. The KAP family NTPases are sporadically distributed across a wide phylogenetic range in bacteria but among the eukaryotes are represented only in animals. Many of the prokaryotic KAP NTPases are encoded in plasmids and tend to undergo disruption to form pseudogenes. A unique feature of all eukaryotic and .