SIRP-δ Activators

SIRP-δ (Signal Regulatory Protein Delta) is a transmembrane protein belonging to the signal-regulatory protein (SIRP) family, which is part of the immunoglobulin superfamily. Proteins in this family are characterized by their extracellular domains containing immunoglobulin-like structures and their involvement in the regulation of immune cell signaling. SIRP-δ, like its more widely studied family members SIRP-α and SIRP-β, is thought to contain similar structural domains, including an extracellular region with immunoglobulin-like domains, a transmembrane region, and a cytoplasmic tail.

The SIRP family members are known to play significant roles in the modulation of immune responses, particularly in the inhibition of phagocytosis, signal transduction, and the regulation of cell adhesion and migration. SIRP-α, for example, interacts with CD47, a "don't eat me" signal on cells, to inhibit phagocytosis by macrophages. While SIRP-δ's specific ligands and interacting partners are not as clearly defined as those of SIRP-α, it is postulated that SIRP-δ may participate in similar signaling pathways due to its structural homology.The expression pattern of SIRP-δ is less broad compared to SIRP-α, and its functionality has been less explored. However, based on the common features shared with other SIRP family members, SIRP-δ may be involved in the negative regulation of receptor tyrosine kinase signaling pathways, which could impact processes such as cellular growth and differentiation.