Sandbox 502
From Proteopedia
Lsm
by Kelly Hrywkiw Template:STRUCTURE 4emg
Contents |
Introduction
Sm-like (Lsm) proteins most closely resemble Sm proteins, both of which are found in all three domains of life (Wu). Sm proteins play a large role in spliceosome biogenesis through mediating U1, U2, U4, U5, and U6 snRNP assembly. The Sm proteins can be broken down into seven specific proteins (SmB, SmD1, SmD2, SmD3, SmE, SmF, and SmG in humans) all of which share a conserved Sm motif. The Lsm proteins also share the Sm motif, with a total of nine specific Lsm proteins found in yeast (Lsm1-Lsm9). The Lsm proteins 2-7 most closely resemble Sm proteins D1-G, where Lsm 1 and 8 most closely resemble the SmB proteins (He). Lsm9 does not appear to resemble any of the Sm proteins, although there have been some related structures found in the archaeal genome (He). Several studies have shown that the Sm proteins form into seven membered rings which bind to the sm binding site, a U rich sequence found in all but U6 snRNA. Similarly, Lsm proteins have been found to associate into three complexes, Lsm2-8, Lsm1-7, and Lsm2-7 (Wu). The exact mechanisms of these complexes are dictated by their composition, structure, and cellular location and their overall functioning in pre-mRNA splicing, mRNA decay, and other additional roles (Wu) (He).
