Monogalactosyl diacylglycerols

Cer. (cerebroside) MGD (monogalactosyl diacylglycerol) SG-Ceram. (sulfogalactosyl ceramide) and SGG-lipid (sulfogalactosyl diacyl-and monacylmonoalkylglycerol). Data in parentheses are duplicate values. The cells were grown in the presence of the [ Hj-galac-tose for 16 hrs. (21) Brain Research, Table I. 

Figure 4. Activities of cerebroside PAPS sulfotransferase (CST) monogalactosyl diacylglycerol PAPS sulfotransferase (MST) and hydroxy fatty acyl ceramide UDP-galactose galactosyltransferase (C Gal. T) in reconstituted homogenates of dissociated brain cells from 15-day embryonic mice grown for varying days in culture. Note that the activity of the galactosyltransferase is expressed on a different scale from that of the sulfotransferase (21).

Enzymatic assay - The in vitro activity of UDP-galactose diacylglycerol galactosyl-transferase (UDGT) was assayed by following the formation of monogalactosyl diacylglycerol as described by Teucher and Heinz (1991). The reaction... 

It is generally accepted that a set of desaturases which is located in the plastids introduces double bonds into the acyl moieties bound as thioesters to acyl carrier protein or as oxoesters in monogalactosyl diacylglycerols. Both saturated and unsaturated fatty acids are translocated as acyl-CoAs from the plastids to the endoplasmic reticulum. Acyl chains of these activated fatty acids are elongated or incorporated into phosphatidylchohnes and other polar lipids II (cf. Fig. 1), and partly modified, for example, by desaturation. Further modification of acyl moieties leads to hydroxy-, epoxy-, and cyclic fatty acids. 

TABLE 1. Diffraction spacings obtained from the different phases formed aqueous diversions of saturated monogalactosyl-diacylglycerol. 

El-Hafid L, Pham Thi AT, Zuily-Fodil Y, Vieira da Silva J. Enzymatic breakdown of polar lipids in cotton leaves under stress degradation of monogalactosyl-diacylglycerol. Plant Physiol Biochem 1989 27 495-502. 

---