Chemistry Reference
In-Depth Information
Figure 25.1
Illustration of effect of ganglioside
GM1-binding human lectins on cell growth and
morphology of human neuroblastoma cells
(SK - N - MC) in culture. Untreated controls (a)
are compared with cell populations exposed to
galectins - 1 and - 3 at 125
μ
g/ml (b and c) and
galectin-1 in the presence of a 10-fold excess of
galectin - 3 (D) for 48 h; magnifi cation:
×
125.
presentation of ganglioside GM1 (for details on glycosphingolipids, please see
Chapters 10 and 30). Will there be an endogenous protein reading this sugar-
encoded message? Figure 25.1 illustrates the effect that a cross- linking human
lectin (galectin-1) has on cell cultures (for crystal structure of this lectin, please
see Figure 13.2; a survey of its natural ligands is presented in Table 19.3).
Importantly, this lectin is expressed by the neuroblastoma cells and its cell
surface presentation follows the course of ligand generation - a convincing case
of coregulation [11]. The same players can also originate from two different cell
types, as is the case in cross-talk between T regulatory cells, the source of
galectin-1, and T effector cells presenting the ganglioside [12]. The knowledge
of the presence of other galectins (please see Chapter 19 and also Chapter 27.5 )
inspired us to probe into the possibility of functional antagonism. Indeed, the
detection of competitive inhibition by another member of this lectin family, the
