Exhibit 10.20
 
PRENTISS PROPERTIES ACQUISITION PARTNERS, L.P.
 
Fourth Amendment to the Third Amended and Restated Agreement of Limited
Partnership of Prentiss Properties Acquisition Partners, L.P.
 
RECITALS
 
Belmar Real Estate Corporation desires to assign and Belrose Realty Corporation
(“Assignee”) desires to acquire 350,000 8.30% Series B Preferred Units of the
Partnership.
 
Pursuant to Article XI of the Third Amended and Restated Agreement of Limited
Partnership, dated as of October 1, 2001, as amended by amendments dated
December 18, 2001, January 3, 2002 and March 19, 2002 (as so amended, the
“Agreement”), of the Partnership, Prentiss Properties I, Inc. as the sole
general partner of the Partnership (the “General Partner”), desires to amend the
Agreement to admit Assignee as a Substitute Limited Partner with respect to the
Assigned Units; terms being used herein as defined in the Agreement.
 
NOW, THEREFORE, the General Partner hereby adopts the following amendment to the
Agreement.
 
1.    Exhibit A to the Agreement is hereby amended and restated in its entirety
as set forth on Exhibit A attached hereto.
 
2.    Notwithstanding anything to the contrary in Section 4.02 (d) (viii) or
elsewhere in the Agreement, none of the 8.30% Series B Preferred Units held by
Belrose Realty Corporation may be exchanged for Series B Preferred Shares prior
to January 1, 2012.
 
3.    Assignee accepts and agrees to be bound by the terms and provisions of the
Agreement.
 
[Signature Page Follows]
 

1

--------------------------------------------------------------------------------

 
IN WITNESS WHEREOF, the General Partner, Assignor and the Assignee have executed
this Fourth Amendment as of July 30, 2002.
 
GENERAL PARTNER
PRENTISS PROPERTIES I, INC.
By:
 
/s/    MICHAEL A. ERNST         

--------------------------------------------------------------------------------

   
Name:    Michael A. Ernst
Title:    Executive Vice President Chief Financial Officer
ASSIGNEE AND SUBSTITUTE LIMITED PARTNER:
BELROSE REALTY CORPORATION
By:
 
/s/    WILLIAM R. CROSS         

--------------------------------------------------------------------------------

   
Name:    William R. Cross
Title:    Vice President
ASSIGNOR:
BELMAR REALTY CORPORATION
By:
 
/s/    WILLIAM R. CROSS         

--------------------------------------------------------------------------------

   
Name:    William R. Cross
Title:    Vice President

2