Molecular probe for imaging of pancreatic islet and the precursor, and use of the same

A precursor of a molecular probe for imaging of pancreatic islets, the precursor comprising any one of the following polypeptides:

• a polypeptide represented by any one of the following formulae (1) to (4),
• a polypeptide obtained by deletion, insertion, or substitution of one to several amino acids with respect to a polypeptide represented by any one of the following formulae (1) to (4), the polypeptide being capable of binding to pancreatic islets after being labeled and deprotected, and
• a polypeptide having a homology of 80% or higher with any one of the amino acid sequences of polypeptides represented by the following formulae (1) to (4), the polypeptide being capable of binding to pancreatic islets after being labeled and deprotected,
• wherein the molecular probe is used in imaging of pancreatic islet, wherein
• (SEQ ID NO. 1)
• *-DLSK* QMEEEAVRLFIEWLK* NGGPSSGAPPPSK-NH2
• (1)
• (SEQ ID NO. 2)
• *-LSK* QMEEEAVRLFIEWLK* NGGPSSGAPPPSK-NH2
• (2)
• (SEQ ID NO. 3)
• *-SK* QMEEEAVRLFIEWLK* NGGPSSGAPPPSK-NH2
• (3)
• (SEQ ID NO. 4)
• *-K* QMEEEAVRLFIEWLK* NGGPSSGAPPPSK-NH2
• (4)
• in the formulae (1) to (4), *- indicates that an α-amino group at an N-terminus is protected by a protecting group or modified with a modifying group having no electric charge, K* indicates that an amino group of a side chain of a lysine is protected by a protecting group, and —NH2 indicates that a carboxyl group at a C-terminus is amidated.