Based on which literature source do you say " 60 kDa may represent the molecular weight of LEDGF protein without SRD domain" ?
I did not understand what do you mean by conjugated LEDGF protein, with what its conjugated ?
SRD is a part of LEDGF/p75 itself (present roughly at the central region of it; amino acid position ranging from 200 to 336 of 528, total number amino acids; Source pubmed id - 21345933 )
SRD domain was recently identified to play a role in localization of LEDGF/p75 and its binding partners to the active target regions (which are identified by histone markers like acetylation, methylation), especially with HIV-1 Integrase protein. Without SRD domain it losses it main role. There are only two splice variants of this protein, the other differ at the C-terminal end.