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II VNDBOOK OF I'lIYSXH (>(,N 



NEfKOFHYSIOLOGY III 



1 Alii F. 3. .1. (.'iirn/iumrih o) ( ,i,hinl Pintails* 

 Type 



Characteristics 



Mbumin 



Globulin 



Collagen and elastin 



kibomu Icoprotcin 



I leoxyribonucleoprotein 



Liponuclcoprotein 



Phosphoprotcin 

 Proteolipids 



Neurokeratin 



Restricted to nonneural elements (blood vessels, etc.) 



Mainly in cytoplasm 



Only in nucleus 



Lipid content 35' , 1 phosphatides, cerebrosides) ; accounts for majority of protein-P 



Similar concentration in gray and white 



Type A (mixture) : 20' , protein; 8o f , lipid (cerebrosides and phosphatides, ratio 7:1) 



Type B: 50' t protein; 50' , lipid ( phosphatides and cerebrosides, ratio 6:4 with half the phosphatide 



as sphingomyelin 1 

 Type C: 75' , protein, 25' , lipid (glycerophosphatid.es) 

 Concentration of white vs. gray 4:1 ; a major component of tissue solids; protein moiety trypsin 



resistant (? = neurokeratin) 

 ? same as proteolipid 



B. Electrophoresis »/ Water-Soluble Cerebral Proteins 



. Graj 



0.6 

 ..9 



4 - 



7.8 



66.6 



.8.9 



* References: 68, 72, 77, 96, 97, 106, 141, 144, )-,j. 



■-, White 



I . 1 



30 



7-2 



it. 7 

 53" 

 ^3-4 



Comment 

 Present in CSF 



Lipoprotein in serum; glycoprotein in serum 

 Glycoprotein in brain 

 Lipoproteins in serum and brain 



these observations, diagrams, such as those shown in 

 figure 3, have been proposed. They cannot be taken 

 literally but should be considered to represent a 

 prototype or principle of organization. Finean (62) 

 suggested a modification (figure 3/J1 of Schmitt's 

 (203) earlier conception to account for certain 

 findings in x-ray diffraction patterns and, in doing 

 so, has proposed a role for the cholesterol of the 

 invelin sheath, as illustrated. Basically the structure 

 is visualized as consisting of bimolecular lipid layers 

 oriented radially (to the long axis of the liber) be- 

 tween concentrically oriented protein chains and 

 incorporating thin water channel-. I'hese le, diets or 

 period-,' measuring about 170 A in length, appear 

 in be wrapped around die axon a- laminations. This 

 lamellar arrangement can be seen by electron 

 microscopy, (bo, In, 17.', 197). Finean (64) has 

 repoi ted that, although the basic pattern of myelin is 

 -imilar for both peripheral and central structures, 

 the latter appear- to be only lipid in 1 haracter, while 

 the former i- composed oi lipoprotein. Geren (85) 

 has demonstrated thai the peripheral myelin sheath 

 i- actually produced by and pari ol the Schwann cell 

 membrane. It is probable, but not yet firmly es- 



tablished, that a similar function for oligodendroglia 

 obtains for central myelinated tracts. 



proteins. By comparison with the lipids, informa- 

 tion concerning cerebral protein- i- -cant indeed. Satis- 

 factory methods for protein chemistry are a relatively 

 recent development and the associati on of many 

 cerebral proteins with lipids has compl v cated appli- 

 cation of these method-. A number of protein com- 

 ponent- have been isolated from the brain by various 

 methods, but the relative amounts and distribution 

 are in most cases unknown or uncertain. The known 

 components are listed in table 3, together with some 

 of their characteristic-. Electrophoresis has recently 

 been applied to cerebral tissues and the results of 

 one such analysis are also given in the table. Com- 

 parison of the latter data with analyses on serum 

 protein show- a pattern, which i- encountered in 



most tissues, of low albumen and high globulin 

 percentages, especially for the f}-globulin fractions 



which contain the main lipoprotein components. 

 The correlation of clcctiophorclic analyses with the 

 components isolated cannot It established a( this 

 t ime. 

 ( )f principal interest for the central nervous system 





