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SBC seminar series, 2013

Every second Tuesday, at 10:30.
Lunch room floor 2, Science for Life Laboratory, Tomtebodavägen 23A, Solna.
Please note: Time and location may vary; please check the information below

Seminars by external speakers are scheduled as long in advance as possible, while those by internal SBC speakers are only scheduled for two months ahead and are held according to a rolling schedule. If you want additional information about the SBC seminars by email, please join our mailing list seminars@sbc.su.se.


(List of previous seminars from 2013 is here).
Wednesday December 1810:00 Sofia HaglundStockholm University
Lunch room at Scilifelab, alpha floor 2 Identification and characterization of some of the most topologically varied membrane protein families
Membrane proteins are essential for life. It has been estimated that about a quarter of all human genes are encoding membrane proteins and they play a vital role in many biological processes. The specific environment of the membrane proteins puts constrains to their structures and let them generally be composed of a set of transmembrane helices connected by loops locating either inside or outside of the membrane. Such structures can therefore be described as topologies. The topology of membrane proteins within protein families are thought to be conserved in evolution due to the notion that structure is more conserved than sequence. However, recent studies show that topology variation such as internal gene duplication and topology inversion do exist among homologous proteins. Nevertheless, a systematic study of the topology variation within protein families is lacking. Here, we identify four protein families that are among the most topologically varied protein families by multiple alignment of topologies within proteins families aided by the phylogenetic tree. They are Mechanosensitive ion channel (PF00924), Cytochrome C assembly protein (PF01578), MotA/TolQ/ExbB proton channel family (PF01618), and (FtsX-like permease family) PF02687. We show that the topology in PF00924, PF01578 and PF01618 varies mostly by insertions/deletions of a few transmembrane helices at the N- or C-termini, and PF02687 varies mostly by internal gene duplication. Finally, the potential biological background to the topology variation in these families is also discussed.


Previous seminars at SBC: 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 and 2012.

Viktor Granholm

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