BMC Genomics Research article Functional diversity of human protein kinase splice variants marks significant expansion of human kinome Krishanpal Anamika1,2, Nicolas Garnier1 and Narayanaswamy Srinivasan*1 BioMed Central Open Access Address: 1Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India and 2Current address: Department of Functional Genomics, Institute for Genetics and Molecular and Cellular Biology, 1 rue Laurent Fries/BP 10142/67404 Illkirch Cedex Strasbourg, France Email: Krishanpal Anamika - anamika@igbmc.fr; Nicolas Garnier - nicolas@mbu.iisc.ernet.in; Narayanaswamy Srinivasan* - ns@mbu.iisc.ernet.in * Corresponding author Published: 22 December 2009 BMC Genomics 2009, 10:622 doi:10.1186/1471-2164-10-622 Received: 22 June 2009 Accepted: 22 December 2009 This article is available from: http://www.biomedcentral.com/1471-2164/10/622 © 2009 Anamika et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Abstract Background: Protein kinases are involved in diverse spectrum of cellular processes. Availability of draft version of the human genomic data in the year 2001 enabled recognition of repertoire of protein kinases. However, over the years the human genomic data is being refined and the current release of human genomic data has helped us to recognize a larger repertoire of over 900 human protein kinases represented mainly by splice variants. Results: Many of these identified protein kinases are alternatively spliced products. Interestingly, some of the human kinase splice variants appear to be significantly diverged in terms of their functional properties as represented by incorporation or absence of one or more domains. Many sets of protein kinase splice variants have substantially different domain organization and in a few sets of splice variants kinase domains belong to different subfamilies of kinases suggesting potential participation in different signal transduction pathways. Conclusions: Addition or deletion of a domain between splice variants of multi-domain kinases appears to be a means of generating differences in the functional features of otherwise similar kinases. It is intriguing that marked sequence diversity within the catalytic regions of some of the splice variant kinases result in kinases belonging to different subfamilies. These human kinase splice variants with different functions might contribute to diversity of eukaryotic cellular signaling. Background Protein kinases represent one of the largest protein domain families in most of the higher eukaryotes. Mem- bers of protein kinase family are involved in innumerable signal transduction pathways contributing in the decision making on variety of cellular processes such as cell growth, development, differentiation, metabolism, cell communication and apoptosis. Availability of the first draft version of the human genomic data in the year 2001 [1] provided opportunity to recognize the repertoire of protein kinases in the human [2-4]. These studies employed bioinformatics approaches to recognize kinases starting from the genomic data and provided a classifica- tion of kinases that give hint to the signal transduction pathways in which the kinases participate. Due to differ- ences in the human genome data set employed and also due to different bioinformatics approaches employed by different groups the number of protein kinases reported in these early publications differed slightly though a vast majority of kinases forming a common set [5]. Page 1 of 7 (page number not for citation purposes)