SerpinB11 is a serine proteinase inhibitor of the ovalbumin-like B clade of serpins. It was first discovered in human lung and prostate. Little is known about SerpinB11 tissue distribution and function. Splice variants of 305, 278 and 190 amino acids have been reported, with predicted masses of 33.97, 31.6 and 21.1 kDa respectively, and pIs of 8.11, 9.03 and 6.07 respectively. The 305 and 190 amino acid forms share the same aminoterminus as the 392 amino acid form. The 305 amino acid form has a deletion in residues 120-206, of the 392 amino acid form. The 190 amino acid form has a deletion in residues 57-259 relative to the long form. The 278 amino acid form starts at the third methionine, relative to the long form. All four forms contain the reactive center loop of the long form, but it is unknown if the shorter forms are active serpins. The predicted isoelectric points of SerpinB11 are significantly more basic than the other B clade serpins, and suggest a different localization or function for this serpin.
