Identification Of Keratin In Cashmere And Wool Fibers Based On Label-free Quantitative SWATH Method

The cashwool of Inner Mongolia cashless goat is famous in the world for its high yield and good quality.It is known as "fiber gem" and "soft gold" in textile raw materials.The indumentum type of cashmere goats belongs to heterogeneous indumentum.Hair is produced by primary hair follicles and cashmere is produced by secondary hair follicles.In order to excavate the proteins that affect the structure of cashmere and wool fibers,the phenotypic traits and protein molecular composition of cashmere and wool fibers in Inner Mongolia cashmere goats were determined.Firstly,the length,fineness and strength of cashmere and wool fibers were measured to determine the phenotypic differences between them.Secondly,the protein library of cashmere and wool fibers was established by data dependent acquisition(IDA).Then,based on the label-free quantitative(SWATH)method,the differential proteins of cashmere and wool fibers were discovered,and the differential proteins were functionally analyzed to screen out the characteristic proteins of cashmere and wool.Finally,the function of the characteristic protein KRT1 was studied.Coimmunoprecipitation(CO-IP)method was used to find out the associated proteins that form fiber structure differences.The expression of KRT1 protein was analyzed by Western blot.The specific results are as follows :1.The structure,length,fineness and strength of cashmere fiber and wool fiber were measured : the scale structure of cashmere fiber was coronal,and the scale structure of wool fiber was flat.The average fiber diameter and the coefficient of variation of fiber diameter of cashmere was significantly smaller than that of wool(P <0.01).Breaking strength and breaking elongation(c N)of cashmere fibre significantly less than wool fibers(P < 0.01);The length of wool fiber was significantly lower than that of cashmere(P <0.01).2.Identification of total protein of cashmere and wool fiber in Inner Mongolia cashmere goat : 108 proteins,886 peptides and 2787 maps were detected in cashmere fiber species;116 proteins,841 peptides and 2353 profiles were detected in wool fiber.A total of 141 proteins,1189 peptides and 5601 profiles were detected in the total proteins of the two fibers.19 keratin(KRT)and 5 keratin associated protein(KRTAP)were found in cashmere.21 KRTs and 2 KRTAPs were identified in wool fiber.3.GO functional analysis of the total protein of pilose and hair fibers enriched 13 biological processes(BP),among which keratinocyte differentiation,intermediate filament bundle assembly,intermediate filament organization,establishment of skin barrier were structurally related.9 cellular components(CC),including intermediate filament,keratin filament;there are 10 molecular functions(MF),including structural molecule activity,structural constituent of epidermis,and structural constituent of muscle.4.A total of 39 differentially expressed proteins in different fibers of Inner Mongolia cashmere goats were screened by SWATH method,including 18 up-regulated proteins and21 down-regulated proteins.10 proteins related to structure,trait and function were screened out.Among them,there are 5 proteins highly expressed in cashmere fibers,namely : KRT14、KRT17、KRT75、KRT38、KRTAP8-1;there are five proteins highly expressed in wool fibers : KRT5、KRT77、KRT1、KRT10 and KRT79.5.The KRT1 protein was subjected to co-immunoprecipitation assay,and 27 proteins,101 peptides,and 1409 spectra were identified(under 1 % FDR conditions).The proteinprotein interaction network prediction map was constructed by STRING software.The results showed that KRT1 had a strong targeting relationship with KRT14,KRT17 and KRT18 in the hair fibers of Inner Mongolia cashmere goats.The expression of KRT1 protein in cashmere and wool fibers was detected by Western Blot.The results showed that the expression of KRT1 protein in wool fibers was significantly higher than that in cashmere,which was consistent with the proteomic results.This study clarified the proteins that constitute the structure of cashmere and wool and their interrelationships,laying a foundation for the formation mechanism of cashmere quality traits and marker-assisted development.