TY - JOUR

T1 - Expression of spasmolysin (FIM-A.1)

T2 - an integumentary mucin from Xenopus laevis

AU - Hauser, F

AU - Gertzen, E M

AU - Hoffmann, W

PY - 1990/8

Y1 - 1990/8

N2 - In the past, a unique type of precursor for a secretory protein was discovered. It contains a central repetitive domain rich in threonine residues and terminal cysteine-rich domains. Due to striking homologies of these terminal domains with pancreatic spasmolytic polypeptide, originally the name "prepro-spasmolysin" was proposed. Here we show that the mature protein has a MW of about 130 kDa, consisting of about 70% carbohydrate and 30% protein. Similar O-linked glycoproteins have been found in mucins from human intestine. For this and numerous other reasons we decided to rename this glycoprotein "frog integumentary mucin A.1" (FIM-A.1). Furthermore, analysis of the protein with specific antibodies against the predicted C-terminal end indicates that FIM-A.1 is probably not processed at pairs of basic residues. In situ hybridization as well as immunofluorescence studies revealed that FIM-A.1 is expressed and stored exclusively in mature mucous glands of Xenopus laevis skin. Only cone cells at the proximal part of these glands do not synthesize FIM-A.1. In contrast, all other physiologically active peptides from X. laevis skin investigated so far are synthesized in granular glands. A hypothetical function of FIMs for defense against microbial infections is discussed.

AB - In the past, a unique type of precursor for a secretory protein was discovered. It contains a central repetitive domain rich in threonine residues and terminal cysteine-rich domains. Due to striking homologies of these terminal domains with pancreatic spasmolytic polypeptide, originally the name "prepro-spasmolysin" was proposed. Here we show that the mature protein has a MW of about 130 kDa, consisting of about 70% carbohydrate and 30% protein. Similar O-linked glycoproteins have been found in mucins from human intestine. For this and numerous other reasons we decided to rename this glycoprotein "frog integumentary mucin A.1" (FIM-A.1). Furthermore, analysis of the protein with specific antibodies against the predicted C-terminal end indicates that FIM-A.1 is probably not processed at pairs of basic residues. In situ hybridization as well as immunofluorescence studies revealed that FIM-A.1 is expressed and stored exclusively in mature mucous glands of Xenopus laevis skin. Only cone cells at the proximal part of these glands do not synthesize FIM-A.1. In contrast, all other physiologically active peptides from X. laevis skin investigated so far are synthesized in granular glands. A hypothetical function of FIMs for defense against microbial infections is discussed.

KW - Amino Acid Sequence

KW - Animals

KW - Base Sequence

KW - Electrophoresis, Polyacrylamide Gel

KW - Fluorescent Antibody Technique

KW - Immune Sera

KW - Molecular Sequence Data

KW - Molecular Weight

KW - Mucins/analysis

KW - Mucous Membrane/cytology

KW - Oligonucleotide Probes

KW - Oligopeptides/chemical synthesis

KW - Recombinant Fusion Proteins/analysis

KW - Skin/cytology

KW - Xenopus Proteins

KW - Xenopus laevis

U2 - 10.1016/0014-4827(90)90230-8

DO - 10.1016/0014-4827(90)90230-8

M3 - Journal article

C2 - 2196180

VL - 189

SP - 157

EP - 162

JO - Experimental Cell Research

JF - Experimental Cell Research

SN - 0014-4827

IS - 2

ER -