日韩av大片在线观看欧美成人不卡|午夜先锋看片|中国女人18毛片水多|免费xx高潮喷水|国产大片美女av|丰满老熟妇好大bbbbbbbbbbb|人妻上司四区|japanese人妻少妇乱中文|少妇做爰喷水高潮受不了|美女人妻被颜射的视频,亚洲国产精品久久艾草一,俄罗斯6一一11萝裸体自慰,午夜三级理论在线观看无码

Siglec-2, also known as CD22, is a type I transmembrane protein belonging to the immunoglobulin superfamily and functions as an inhibitory lectin on B cells. It is characterized by its ability to bind α2,6-linked sialic acid on the same （cis） or adjacent （trans） cells. CD22 plays a crucial role in mediating B cell interactions, directing B cell localization within lymphoid tissues, and regulating B cell antigen receptor signaling. The protein contains four immunoreceptor tyrosine-based inhibitory motifs （ITIMs）, allowing it to recruit cytoplasmic phosphatases to inhibit downstream signaling pathways. Additionally, CD22 can form cis interactions with sialylated glycoproteins such as CD45, potentially masking its sialic acid recognition site. Its complex interactions with various signaling molecules highlight its multifaceted role in B cell regulation and immune responses.