Not sure why you are after 500hrs PIC for an ATPL. I have pasted in the ATPL requirements from FCL1 for you. 1.280 is the relevent bit.
JAR–FCL 1.265 Minimum age An applicant for an ATPL(A) shall be at least 21 years of age.
JAR–FCL 1.270 Medical fitness An applicant for an ATPL(A) shall hold a valid Class 1 medical certificate. In order to exercise the privileges of the ATPL(A) a valid Class 1 medical certificate shall be held. [Amdt. 1, 01.06.00]
JAR–FCL 1.275 Privileges and conditions (a) Privileges. Subject to any other conditions specified in JARs, the privileges of the holder of an ATPL(A) are to: (1) exercise all the privileges of the holder of a PPL(A), a CPL(A) and an IR(A); and (2) act as pilot-in-command or co-pilot in aeroplanes engaged in air transportation. (b) Conditions. An applicant for an ATPL(A) who has complied with the conditions specified in
JAR–FCL 1.265, 1.270 and 1.280 through 1.295 shall have fulfilled the requirements for the issue of an ATPL(A) containing a type rating for the aeroplane type used on the skill test.
JAR–FCL 1.280 Experience and crediting (See JAR–FCL 1.050(a)(3)) (a) An applicant for an ATPL(A) shall have completed as a pilot of aeroplanes at least 1500 hours of flight time (see also JAR-FCL 1.050(a)(3)). [Of the 1 500 hours flight time, up to 100 hours of flight time may have been completed in FS and FNPT of which a maximum of 25 hours may have benn completed in FNPT,] including at least: (1) 500 hours in multi-pilot operations on aeroplanes type certificated in accordance with the JAR/FAR?E5 Transport category or the JAR/FAR?E3 Commuter category, or BCAR or AIR 2051; (2) 250 hours either as pilot-in-command or at least 100 hours as pilot-in-command and 150 hours as co-pilot performing, under the supervision of the pilot-in-command the duties and functions of a pilot-in-command provided that the method of supervision is acceptable to the Authority; (3) 200 hours of cross-country flight time of which at least 100 hours shall be as pilot-in-command or as co-pilot performing under the supervision of the pilot-in-command the duties and functions of a pilot-in-command, provided that the method of supervision is acceptable to the Authority; (4) 75 hours of instrument time of which not more than 30 hours may be instrument ground time; and (5) 100 hours of night flight as pilot-in-command or as co-pilot. (b) (1) Holders of a pilot licence or equivalent document for other categories of aircraft will be credited with flight time in such other categories of aircraft as set out in JAR–FCL 1.155 except flight time in helicopters which will be credited up to 50% of all the flight time requirements of sub-paragraph (a). (2) Holders of a flight engineer licence will be credited with 50% of the flight engineer time up to a maximum credit of 250 hours. This 250 hours may be credited against the 1 500 hours requirement of sub-paragraph (a), and the 500 hours requirement of sub-paragraph (a)(1), provided that the total credit given against any of these sub-paragraphs does not exceed 250 hours. (c) The experience required shall be completed before the skill test given in JAR–FCL 1.295 is taken. [Amdt. 1, 01.06.00; Amdt. 3, 01.07.03]
You can find the FCL1 part 1 document on line at the JAA web site here
http://www.jaa.nl/section1/jarsec1.html