ABO血型的分子本质是什么？为什么O型个体的血浆里天然存在抗A与抗B抗体？
What is the molecular essence of the ABO blood groups, and why does plasma from type O individuals naturally contain anti-A and anti-B antibodies?
ABO差异源于红细胞表面糖链末端的一个糖基：以H抗原为前体，A酶在其上添加N-乙酰半乳糖胺生成A抗原，B酶添加半乳糖生成B抗原；O型的转移酶基因突变失效，仅保留H抗原。肠道菌群带有相似的糖结构，持续刺激机体产生针对自身所缺抗原的“天然抗体”，因此异型输血必须严格配型。
The ABO difference reduces to one terminal sugar on red-cell surface glycans. Starting from the H antigen, the A enzyme adds N-acetylgalactosamine to build the A antigen and the B enzyme adds galactose; in type O people the transferase gene is inactivated, leaving bare H antigen. Gut microbes display similar sugar motifs, continuously priming natural antibodies against whichever antigen a person lacks, so non-matched transfusion must be avoided.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Yamamoto、Clausen、White 与 Hakomori：《组织血型ABO系统的分子遗传基础》，Nature，1990
Yamamoto, Clausen, White & Hakomori, 'Molecular genetic basis of the histo-blood group ABO system', Nature, 1990
独立核验依据 · Independent verification: 核验依据 1 CROSSREF 标识 10.1038/345229a0：Molecular genetic basis of
#糖生物学 #ABO血型 #糖基转移酶
禽流感病毒很难感染人，人流感病毒也难得感染禽类——这道物种屏障的秘密竟藏在细胞糖链的一种连接方式里，为什么？
Avian influenza viruses rarely infect humans, and human strains seldom infect birds — the secret of this species barrier lies in how a cell-surface sugar chain is linked. Why?
流感病毒血凝素（HA）用受体结合位点抓住细胞表面的唾液酸，而亲和力取决于唾液酸与下一个糖的连接方式：禽型HA偏好α2,3连接（集中于禽类肠道），人型HA偏好α2,6连接（富集于人上呼吸道）。该特异性仅由HA少数氨基酸决定；禽病毒一旦突变出识别人型受体的能力，便可能跨种传播，这是迈向大流行的关键一步。
Viral hemagglutinin grips sialic acid on the cell surface through its receptor-binding site, and its affinity depends on the linkage between sialic acid and the next sugar. Avian-type HA favors α2,3-linked receptors, concentrated in the bird gut; human-type HA favors α2,6-linked receptors, dense in the human upper airway. Only a few amino acids in HA set this specificity; once an avian virus mutates to recognize human-type receptors it can jump species — the pivotal step toward pandemic potential.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-02
来源 · Source
Skehel 与 Wiley：《病毒入侵中的受体结合与膜融合：流感血凝素》，Annual Review of Biochemistry，2000
Skehel & Wiley, 'Receptor binding and membrane fusion in virus entry: the influenza hemagglutinin', Annual Review of Biochemistry, 2000
独立核验依据 · Independent verification: 核验依据 1 CROSSREF 标识 10.1146/annurev.biochem.69.1.531：Receptor Bi
#糖生物学 #唾液酸 #血凝素
细胞里的水解酶具有腐蚀性，必须准确送达溶酶体。细胞用什么机制防止这些酶被误送到细胞外？这个“地址标签”出错会导致什么疾病？
Digestive hydrolases inside cells are corrosive and must reach the lysosome precisely. What mechanism stops these enzymes from being shipped outside the cell by mistake, and what disease results when the address label fails?
在高尔基体内，GlcNAc-磷酸转移酶给可溶性水解酶的N-连接聚糖接上磷酸甘露糖，形成甘露糖-6-磷酸（M6P）标签；M6P受体识别标签，把酶装进囊泡定向送往溶酶体。若标记酶系发生突变，酶会被当作分泌物排到胞外，溶酶体内底物堆积形成包涵体，即I-细胞病，患者出现骨骼畸形与发育迟缓。
In the Golgi apparatus, GlcNAc-phosphotransferase adds phosphorylated mannose to the N-linked glycans of soluble hydrolases, creating mannose-6-phosphate (M6P) tags. M6P receptors recognize the tag and pack the enzymes into vesicles bound for lysosomes. When the tagging machinery is mutated, enzymes are secreted instead, undigested substrate accumulates as inclusion bodies, and the result is I-cell disease, marked by skeletal abnormalities and delayed development.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Kornfeld, S. & Mellman, I. (1989), The biogenesis of lysosomes, Annual Review of Cell Biology 5: 483–525
Kornfeld, S. & Mellman, I. (1989), The biogenesis of lysosomes, Annual Review of Cell Biology 5: 483–525
独立核验依据 · Independent verification: 核验依据 1 DOI 10.1146/annurev.cellbio.5.1.483
#糖生物学 #甘露糖-6-磷酸 #溶酶体靶向