TABLE 1.

PRE activities of subfragments^a

Constructb	Varc	No. of variegating lines/no. of lines tested with heterozygous mutationd:						Polytenese	Maintenancef
		Pc3	Psc1	Su(z)21	E(z)1	trxE2	TrlR85
HA×4	8/22	—g	—	—	—	—	—	—
AB×6	11/27	3/6	1/6	3/6	5/6	5/6	0/5	0/2
BP×6	15/20	6/11	6/11	6/11	4/11	2/8	1/8	1/2
YGBP×6	19/20	3/6	4/6	4/6	—	—	3/6	2/3
YGBP×1	5/14	—	—	—	—	—	—	—
PF×4	22/31	3/12	7/12	8/13	2/12	3/9	0/9	3/5
HH2×4	4/12	—	—	—	—	—	—	—
HS×3	11/32	—	—	—	—	—	—	—
AB×6 S2 Ubx-lacZ	4/8								0/6
BP×6 S2 Ubx-lacZ	5/13								5/13
PF×4 S2 Ubx-lacZ	4/8								0/5

^aFor each fragment, the ability to induce variegated expression of the miniwhite gene in the CaSpeR4 vector was tested. 

^bOligomerization is indicated by the number following the multiplication sign. 

^cNumber of lines that variegate or are repressed when homozygous for the transposon/number of lines tested. 

^dMutations Pc³, Psc¹, Su(z)2¹, and Trl^R85 increased pigmentation, and mutations trx^E2 and E(z)¹ decreased it. 

^eNumber of lines in which a PcG binding site on polytene chromosomes was created/number of lines tested. The determination was performed for selected lines in which the transposon was not inserted at an endogenous PcG site by staining with anti-PC antibodies and in some cases also with anti-PSC and anti-SU(Z)2 antibodies. 

^fNumber of lines in which repression was maintained/number of lines tested. The maintenance of repression was determined in embryos of lines containing the PRE fragment in front of an S2 Ubx-lacZ reporter gene. 

^g—, not tested.