>gnl|CDD|146826 pfam04386, SspB, Stringent starvation protein B. Escherichia coli stringent starvation protein B (SspB), is thought to enhance the specificity of degradation of tmRNA-tagged proteins by the ClpXP protease. The tmRNA tag, also known as ssrA, is an 11-aa peptide added to the C terminus of proteins stalled during translation, targets proteins for degradation by ClpXP and ClpAP. SspB a cytoplasmic protein that specifically binds to residues 1-4 and 7 of the tag. Binding of SspB enhances degradation of tagged proteins by ClpX, and masks sequence elements important for ClpA interactions, inhibiting degradation by ClpA. However, more recent work has cast doubt on the importance of SspB in wild-type cells. SspB is encoded in an operon whose synthesis is stimulated by carbon, amino acid, and phosphate starvation. SspB may play a special role during nutrient stress, for example by ensuring rapid degradation of the products of stalled translation, without causing a global increase in degradation of all ClpXP substrates. Length = 152

 Score =  172 bits (439), Expect = 5e-44
 Identities = 56/167 (33%), Positives = 82/167 (49%), Gaps = 15/167 (8%)

Query: 30  IRYDILAKEALRGLVKVVLSEVASIGSLPGEHHFYITFATNARGVRISQNLRKNYPEKMT 89
           I YD L   ALR + + VL++VA  G L  +H  YITF T A GV++   L + YP+ M 
Sbjct: 1   ITYDSLRPYALRAVYRWVLTDVAKEG-LDNDHTPYITFDTTAPGVQVPDELVERYPQIML 59

Query: 90  IVIQNQFWDLKVLDNHFEVGLSFSNVPERLVIPFNAIKGFYDPSVNFELEFDVHIEHIEE 149
            V+Q+ FWDL+V ++ F   L F  VPERL +PF AI  FYDP   F L+F+      +E
Sbjct: 60  NVLQHAFWDLEVGNDGFSFNLRFGGVPERLYVPFAAILAFYDPENGFGLQFEPEEADEDE 119

Query: 150 KLEGGNTGKVLTSPDNFDKNQTNSVSQDSSKKKSTKKQNKNKMASVI 196
                         +  + ++ +    +  + K   K        V+
Sbjct: 120 --------------EEEEDDEADEEDDEDPEPKDPPKTKGRPSLKVV 152