Glycolipids are lipids with an attached carbohydrate or carbohydrate chain. They are widely distributed in every tissue of the body, particularly in nervous tissue such as brain. They occur particularly in the outer leaflet of the plasma membrane, where they contribute to cell surface carbohydrates which form the glycocalyx.

The major glycolipids found in animal tissues are glycosphingolipids. They contain ceramide and one or more sugars. Galactosylceramide (Figure 1) is a major glycosphingolipid of brain and other nervous tissue, found in relatively low amounts elsewhere. It contains a number of characteristic C24 fatty acids, for example, cerebronic acid.

Fig1. Structure of galactosylceramide.

Galactosylceramide can be converted to sulfogalacto sylceramide (sulfatide) which has a sulfo group attached to the O in the three position of galactose and is present in high amounts in myelin. Glucosylceramide resembles galactosyl ceramide, but the head group is glucose rather than galactose. It is the predominant simple glycosphingolipid of extraneural tissues, also occurring in the brain in small amounts. Gangliosides are complex glycosphingolipids derived from glucosyl ceramide that contain in addition one or more molecules of sialic acid. Neuraminic acid (NeuAc) is the principal sialic acid found in human tissues. Gangliosides are also present in nervous tissues in high concentration. They function in cell–cell recognition and communication and as receptors for hormones and bacterial toxins such as cholera toxin. The simplest ganglioside found in tissues is GM3 (see Figure 24–8), which contains ceramide, one molecule of glucose, one molecule of galactose, and one molecule of NeuAc. In the shorthand nomenclature used, G represents ganglioside; M is a monosialo-containing species; and 3 is a number assigned on the basis of chromatographic migration. GM1 (Figure 2), a more complex ganglioside derived from GM3, is of considerable biologic interest, as it is known to be the receptor in human intestine for cholera toxin. Other gangliosides can contain anywhere from one to five molecules of sialic acid, giving rise to di-, trisialogangliosides, etc.

Fig2. GM1 ganglioside, a monosialoganglioside, the receptor in human intestine for cholera toxin.

اخر الاخبار

اخبار العتبة العباسية المقدسة

قسم الشؤون الفكرية يطلق باقة من النشاطات الرقمية الخاصة بشهر المحرم

العتبة العباسية المقدسة تختتم السلسلة الأولى لمشروع المحاضرات القرآنية العاشورائية في بابل

العتبة العباسية المقدسة تسلّم راية العزاء إلى تجمّع مواكب محافظة الديوانية

قسم الشؤون الفكرية يواصل إقامة المجالس الحسينية ضمن سلسلة (بيوت النعيم)

المزيد

الآخبار الصحية

لكبح الجوع وخسارة الوزن.. "سر بسيط" في نظام جوكوفيتش ؟

هل يساعد الرجيم في علاج الأمراض العقلية؟

لحماية أسنان طفلك.. هذا الفيتامين يقلل خطر التسوس

أكل الطعام بسرعة.. طريق سريع إلى أمراض خطيرة

المزيد

الآخبار التكنلوجية

ما هي أفضل درجة حرارة لتكييف الهواء في السيارة؟

ذوبان الأنهار الجليدية يوقظ "عمالقة نائمة"!

9 يوليو يشهد أقصر يوم في التاريخ المسجل ؟!!

راتبه عشرات ملايين الدولارات.. زوكربرغ يخطف "عقل أبل"

المزيد

مواضيع ذات صلة

Phospholipids are The Main Lipid Constituents of Membranes

Fatty Acids are Aliphatic Carboxylic Acids

The Pentose Phosphate Pathway & Other Pathways of Hexose Metabolism: clinical aspects

Galactose is Needed for the Synthesis of Lactose, Glycolipids, Proteoglycans, & Glycoproteins

Ingestion of Large Quantities of Fructose has Profound Metabolic Consequences

Reactions of the Pentose Phosphate Pathway Occur in the Cytosol

Blood Glucose is Derived From the Diet, Gluconeogenesis, & Glycogenolysis

Glycolysis & gluconeogenesis share the same pathway but in opposite directions, & are reciprocally regulated

Glucose-1-Phosphate & Glycogen

Thermodynamic Barriers Prevent a Simple Reversal of Glycolysis

Gluconeogenesis & the Control of Blood Glucose: Biomedical Importance

Glycogen Metabolism is Regulated by A Balance in Activities Between Glycogen Synthase & Phosphorylase