Protein Domain : P domain IPR002884

Type	Domain
Description	In eukaryotes, many essential secreted proteins and peptide hormones are excised from larger precursors by members of a class of calcium-dependentendoproteinases, the prohormone-proprotein convertases (PCs).The P (known as such because it is essential for proteolytic activity), or Homo B, domain of~150 residues is a distinctive characteristic of members of the proprotein convertase family. The P/Homo B domain appears to be necessary to both foldand maintain the subtilisin-like active catalytic module and to regulate its specialized features of calcium and more acidic pH dependence [, , , ].The core of the P/Homo B domain consists of a jelly roll-like fold with eight β-strands. Nonbonded interactions between the catalyticand P/Homo B domains provide additional structural stabilization of the catalytic domains, which alone appear to be thermodynamically unstable [, ].Most of the PC family members contained the cognate integrin binding RGD sequence within the middle of the P domain [ ], which may be requiredfor intracellular compartmentalization and maintenance of enzyme stability within the ER. The integrity of the RGD sequence of proprotein convertase PC1 is critical for its zymogen and C-terminal processing and for its cellular trafficking [ , ]. The carboxy-terminal tail provides uniqueness to each PC family member being the least conserved region of all convertases [].
Short Name	P_dom