The domain within your query sequence starts at position 401 and ends at position 540; the E-value for the 3a1a domain shown below is 8e-55.

SRERMASEVTNNKGNLEDRCLSCGKKNPVSFHPLFEGGLCQSCRDRFLELFYMYDEDGYQ
SYCTVCCEGRELLLCSNTSCCRCFCVECLEVLVGAGTAEDAKLQEPWSCYMCLPQRCHGV
LRRRKDWNMRLQDFFTTDPD

This is a PDB domain - please see the PDBSUM entry of 3a1a for further annotation