Human bile salt-activated lipase: Structural organisation at the C-terminus

Abstract

Bile salt-activated lipase is an abundant human milk protein (Wang and Hartsuck, 1993). The primary structure is known as deduced from cDNA (Nilsson et al., 1990; Hui and Kissel, 1990; Baba et al., 1991; Reue et al., 1991) and expression of the murine (Kissel et al., 1990) and human (Hansson et al., 1993) isoforms have been reported. Structural comparisons show that bile salt-activated lipase is homologous to the cholinesterase protein family over approximately 500 N-terminal residues (Krejci et al., 1991). However, bile salt-activated lipase possesses a unique repeated consensus sequence Gly-Ala-Pro-Pro-Val -Pro-Pro-Thr-Gly-Asp-Ser with minor residue substitutions at the C-terminus. This region is rich in Olinked carbohydrate and the human isoform has the largest number of these repeats with 16 compared to 4 and 3 for the murine and bovine isoforms respectively (Figure 1).