The domain within your query sequence starts at position 504 and ends at position 591; the E-value for the P_proprotein domain shown below is 6.1e-30.

LEHVQFEATIEYSRRGDLHVTLTSAVGTSTVLLAERERDTSPNGFKNWDFMSVHTWGENP
VGTWTLKITDMSGRMQNEGRIVNWKLIL

P_proprotein

P_proprotein
PFAM accession number:PF01483
Interpro abstract (IPR002884):

In eukaryotes, many essential secreted proteins and peptide hormones are excised from larger precursors by members of a class of calcium-dependent endoproteinases, 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 fold and maintain the subtilisin-like active catalytic module and to regulate its specialized features of calcium and more acidic pH dependence [(PUBMED:9636145), (PUBMED:9556596), (PUBMED:12794637), (PUBMED:19654332)].

The core of the P/Homo B domain consists of a jelly roll-like fold with eight beta-strands. Nonbonded interactions between the catalytic and P/Homo B domains provide additional structural stabilization of the catalytic domains, which alone appear to be thermodynamically unstable [(PUBMED:12794637), (PUBMED:19654332)].

Most of the PC family members contained the cognate integrin binding RGD sequence within the middle of the P domain [(PUBMED:10212221)], which may be required for 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 [(PUBMED:9307023), (PUBMED:10212221)]. The carboxy-terminal tail provides uniqueness to each PC family member being the least conserved region of all convertases [(PUBMED:10842308)].

GO process:proteolysis (GO:0006508)
GO function:serine-type endopeptidase activity (GO:0004252)

This is a PFAM domain. For full annotation and more information, please see the PFAM entry P_proprotein