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Partial amino acid sequence of human pancreatic stone protein, a novel pancreatic secretory protein.

ABSTRACT: Pancreatic stone protein (PSP) is the major organic component of human pancreatic stones. With the use of monoclonal antibody immunoadsorbents, five immunoreactive forms (PSP-S) with close Mr values (14,000-19,000) were isolated from normal pancreatic juice. By CM-Trisacryl M chromatography the lowest-Mr form (PSP-S1) was separated from the others and some of its molecular characteristics were investigated. The Mr of the PSP-S1 polypeptide chain calculated from the amino acid composition was about 16,100. The N-terminal sequences (40 residues) of PSP and PSP-S1 are identical, which suggests that the peptide backbone is the same for both of these polypeptides. The PSP-S1 sequence was determined up to residue 65 and was found to be different from all other known protein sequences.

SUBMITTER: Montalto G

PROVIDER: S-EPMC1147119 | biostudies-other | 1986 Aug

REPOSITORIES: biostudies-other

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Project description:The N-terminal 72 residues of an integral membrane fragment, P5, of the human erythrocyte anion-transport protein, which is known to be directly involved in the anion-exchange process, was shown to have the following amino acid sequence: Met-Val-Pro-Lys-Pro-Gln-Gly-Pro-Leu-Pro-Asn-Thr-Ala-Leu-Leu-Ser-Leu-Val-Leu-Met -Ala-Gly-Thr-Phe-Phe-Phe-Ala-Met-Met-Leu-Arg-Lys-Phe-Lys-Asn-Ser-Ser-Tyr-Phe-Pro-Gly-Lys-Leu-Arg-Arg-Val-Ile-Gly-Asp-Phe-Gly-Val-Pro-Ile-Ser-Ile-Leu-Ile-Met-Val-Leu-Val-Asp-Phe-Phe-Ile-Gln-Asp-Thr-Tyr-Thr-Gln- The structure of this fragment was analysed, with account being taken of the constraints that apply to the folding of integral membrane proteins and the topographical locations of various sites in the sequence. It was concluded that this sequence forms two transmembrane alpha-helices. These are probably part of a cluster of amphipathic transmembrane alpha-helices, which could comprise that part of the protein responsible for transport activity. The presently available evidence relating to the anion-exchange process was considered with the structural features noted in this study and a possible molecular mechanism is proposed. In this model the rearrangement of a network of intramembranous charged pairs mediates the translocation of an anion between anion-binding regions at each surface of the membrane, which are composed of clusters of positively charged amino acids. This model imposes a sequential exchange mechanism on the system. Supplementary material, including Tables and Figures describing the compositions of peptides determined by amino acid analysis and sequence studies, quantitative and qualitative data that provide a residue-by-residue justification for the sequence assignment and a description of modifications to and use of the solid-phase sequencer has been deposited as Supplementary Publication SUP 50123 (12 pages) with the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained as indicated in Biochem. J. (1983) 209, 5.

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Partial amino acid sequence of human pancreatic stone protein, a novel pancreatic secretory protein.

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