| Popis: |
The contact site A (csA) glycoprotein is a developmentally regulated cell adhesion molecule (Beug et al. 1973; Muller and Gerisch 1978; Noegel et al. 1985). It is absent from growth-phase cells, and is maximally expressed at the aggregation stage of Dictyostelium discoideum, i.e., during transition from the state of single cells to a multicellular organism (Murray et al. 1981). According to its sequence, the csA protein consists of three regions: a large extracellular N-terminal domain, a proline-, serine-and threonine-rich sequence which resembles the hinge region of immunoglobulins, and a carboxyterminal stretch of hydrophobic amino acids (Noegel et al. 1986). The protein is cotranslationally modified by N-linked carbohydrate residues at the N-terminal domain, and by a ceramide-based phospholipid (PL) anchor (Stadler et al. 1989). The pro/ser/thr-rich stretch of the C-terminal region near to the plasma membrane is decorated with O-linked carbohydrate residues during passage of the protein through the Golgi apparatus, and the N-linked carbohydrate residues are sulfated during the passage (Hohmann et al. 1985; Hohmann et al. 1987b). |
