Amino acid sequence and distribution of mRNA encoding a major skeletal muscle laminin binding protein: an extracellular matrix-associated protein with an unusual COOH-terminal polyaspartate domain.

Abstract

Abstract. Two cDNAs encoding an abundant chicken muscle extracellular matrix (ECM)-associated lamininbinding protein (LBP) have been isolated and sequenced. The predicted primary amino acid sequence includes a probable signal peptide and a site for N-linked glycosylation, but lacks a hydrophobic segment long enough to span the membrane. The COOH terminus consists of an unusual repeat of 33 consecutive aspartate residues. Comparison with other sequences indicates that this protein is different from previously described LBPs and ECM receptors. RNA blot analysis of LBP gene expression showed that LBP mRNA was abundant in skeletal and heart muscle, but barely detectable in other tissues. Blots of chicken genomic DNA suggest that a single gene encodes this LBP. The amino acid sequence and mRNA distribution are consistent with the biochemical characterization described by Hall and co-workers (Hall, D. E., K. A. Frazer, B. C. Hahn, and L. E Reichardt. 1988. J. Cell Biol. 107:687-697). These analyses indicate that LBP is an abundant ECM-associated muscle protein with an unusually high negative charge that interacts with both membranes and laminin, and has properties of a peripheral, not integral membrane protein. Taken together, our studies show that muscle LBP is a secreted, peripheral membrane protein with an unusual polyaspartate domain. Its laminin and membrane binding properties suggest that it may help mediate muscle cell interactions with the extracellular matrix. We propose the name "aspartactin" for this LBP.

Expression of 67 kDa laminin receptor in human breast cancer cells: regulation by progestins

“…This high basal level of laminin attachment of T47Dco cells resembled that of R5020-treated T47D cells. Several potential laminin binding proteins have been identified [7][8][9][10][11][12][13], some of which are /$1-containing integrin complexes [7,42]. To investigate whether the progestin-induced increase in laminin attachment of T47D cells was mediated through /$1 integrin complex, mAb 13, which specifically blocks fll integrin activity [43], was used in the attachment assay.…”

“…As one of the major cell-binding proteins of basement membrane, laminin mediates the attachment of malignant cells to basement membrane [4][5][6]. Several cell surface laminin binding proteins have been identified [7][8][9][10][11][12][13]. Among these, the levels of expression of 67LR have been associated with the metastatic capabilities of tumor cells [5,[14][15][16][17][18][19][20].…”

Overexpression of calsequestrin in L6 myoblasts: formation of endoplasmic reticulum subdomains and their evolution into discrete vacuoles where aggregates of the protein are specifically accumulated.

“…The clones primarily used in this study, generated by infection (Clegg et al, 1988;Muller et al, 1990) and characterized as described previously (Raichman et al, 1995), were the control (mock cells) Cl and the CSQ overexpressor A2. The latter largely resembles clone A3 used by Raichman et al (1995).…”

“…The mechanisms of this group have remained so far largely unknown. Among the ER lumenal proteins devoid of KDEL is calsequestrin (CSQ), the major low-affinity high-capacity Ca2+-binding protein of striated muscle fibers (Fliegel et al, 1987;Clegg et al, 1988;Scott et al, 1988). The distribution of this protein appears peculiar.…”

Caspartin and Calprismin, Two Proteins of the Shell Calcitic Prisms of the Mediterranean Fan Mussel Pinna nobilis

“…Calsequestrin is a high capacity, low affinity calcium-binding protein of the endoplasmic reticulum (59), whereas 4 R. Amons, personal communication. aspartactin is an extracellular matrix protein (60), which binds laminin. Both contain a long C-terminal poly-Asp domain.…”