Protein Modeling on the Internet A group of patients with Crohn disease (an inflammatory bowel disease) underwent biopsies of their intestinal mucosa in an attempt to identify the causative agent. Researchers identified a protein that was present at higher levels in patients with Crohn disease than inpatients with an unrelated inflammatory bowel disease or in unaffected controls. The protein was isolated, and the following partial amino acid sequence was obtained (reads left to right):$\begin{array}{ccc}\text{ EAELCPDRCI }& \text{ HSFQNLGIQC }& \text{ VKKRDLEQAI }\\ \text{ SQRIQTNNNP }& \text{ FQVPIEEQRG }& \text{ DYDLNAVRLC }\\ \text{ FQVTVRDPSG }& \text{ RPLRLPPVLP }& \text{ HPIFDNRAPN }\\ \text{ TAELKICRVN }& \text{ RNSGSCLGGD }& \text{ EIFLLCDKVQ }\\ \text{ KEDIEVYFTG }& \text{ PGWEARGSFS }& \text{ QADVHRQVAI }\\ \text{ VFRTPPYADP }& \text{ SLQAPVRVSM }& \text{ QLRRPSDREL }\\ \text{ SEPMEFQYLP }& \text{ DTDDRHRIEE }& \text{ KRKRTYETFK }\\ \text{ SIMKKSPFSG }& \text{ PTDPRPPPRR }& \text{ IAVPSRSSAS }\\ \text{ KINDAPOPYP }& & \end{array}$ VPKPAPQPYF(a) You can identify this protein using a protein database on the Internet. Some good places to start include Protein Information Resource (PIR; http://pir.georgetown.edu), Structural Classification of Proteins (SCOP; http://scop.mrc-lmb. cam.ac.uk/scop $),$ and Prosite (http://prosite.expasy.org). At your selected database site, follow links to the sequence comparison engine. Enter about 30 residues from the protein sequence in the appropriate search field and submit it for

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