Family S64


Summary Holotypes Alignment Tree Genomes Literature

Summary for family S64

Family type peptidaseS64.001 - Ssy5 peptidase (Saccharomyces cerevisiae), MEROPS Accession MER0043119 (peptidase unit: 459-687)
Content of familyPeptidase family S64 contains endopeptidases.
History Identifier created: MEROPS 7.0 (4 April 2005)
Saccharomyces cerevisiae cells possess a plasma membrane sensor able to detect the presence of extracellular amino acids and then to activate a signalling pathway leading to transcriptional induction of genes that encode an amino acid permease. This sensing function requires the Ssy1, Ptr3 and Ssy5 proteins all of which are essential for activation of the membrane-bound Stp1 transcription factor. The activation is brought about by an endopeptidase cleavage that is mediated by the Ssy5 peptidase (Abdel-Sater et al., 2004).
Catalytic typeSerine
Active site residuesH465 D545 S640 
Active siteCatalytic residues have not been experimentally verified, but some sequences in the C-terminal part of the Ssy5 protein resemble motifs that surround the conserved His, Asp and Ser residues of the active site in family S1 (Abdel-Sater et al., 2004).
Activities and specificitiesThe Ssy5 peptidase is believed to cleave both itself and the Stp1 protein within a motif that is conserved between the two proteins; this contains the sequence PISMS that is required for cleavage to take place (Abdel-Sater et al., 2004).
Molecular structureNo structure is known as yet, but the presence of sequence motifs reminiscent of family S1 suggests that the fold is that of clan PA.
Basis of clan assignmentPredicted active site residues for members of this family and family S1 occur in the same order in the sequence: H, D, S.
Distribution of family Bacteria -  
Archaea -  
Protozoa -  
Fungi details  
Plants -  
Animals -  
Viruses -  
Biological functionsThe Ssy5 peptidase plays a key role in the adaptive response of Saccharomyces cerevisiae, and probably other fungi, to the presence of amino acids in the growth medium.
Statistics for family S64Sequences:40
Identifiers with PDB entries:0
Downloadable files Sequence library (FastA format)
Sequence alignment (FastA format)
Phylogenetic tree (Newick format)
Peptidases and Homologues MEROPS ID Structure
Ssy5 peptidaseS64.001-
family S64 unassigned peptidasesunassigned-